aider: Add read_text function to InputOutput class and --encoding command-line switch.

# Context:
USER: Add a read_text function to the InputOutput class. It takes the file name as argument, and returns the text for that file. Internally, if we get a Unicode error or a FileNotFound error, it prints ToolErrorOutput to notify the user, and then returns None. Add a command-line switch, and dash-dash encoding, which defaults to UTF-8. That's the encoding which will be used by the read_text function.

ASSISTANT: To implement the requested changes, we need to modify the following files:

1. `aider/io.py`: To add the `read_text` function to the `InputOutput` class.
2. `aider/main.py`: To add the `--encoding` command-line switch.

Let's start with the changes to `aider/io.py`:

```python
aider/io.py
<<<<<<< ORIGINAL
class InputOutput:
    num_error_outputs = 0
    num_user_asks = 0

    def __init__(
        self,
        pretty=True,
        yes=False,
        input_history_file=None,
        chat_history_file=None,
        input=None,
        output=None,
        user_input_color="blue",
        tool_output_color=None,
        tool_error_color="red",
    ):
        no_color = os.environ.get("NO_COLOR")
        if no_color is not None and no_color != "":
            pretty = False

        self.user_input_color = user_input_color if pretty else None
        self.tool_output_color = tool_output_color if pretty else None
        self.tool_error_color = tool_error_color if pretty else None

        self.input = input
        self.output = output

        self.pretty = pretty
        if self.output:
            self.pretty = False

        self.yes = yes

        self.input_history_file = input_history_file
        if chat_history_file is not None:
            self.chat_history_file = Path(chat_history_file)
        else:
            self.chat_history_file = None

        if pretty:
            self.console = Console()
        else:
            self.console = Console(force_terminal=False, no_color=True)

        current_time = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
        self.append_chat_history(f"\n# aider chat started at {current_time}\n\n")
=======
class InputOutput:
    num_error_outputs = 0
    num_user_asks = 0

    def __init__(
        self,
        pretty=True,
        yes=False,
        input_history_file=None,
        chat_history_file=None,
        input=None,
        output=None,
        user_input_color="blue",
        tool_output_color=None,
        tool_error_color="red",
        encoding="utf-8",
    ):
        no_color = os.environ.get("NO_COLOR")
        if no_color is not None and no_color != "":
            pretty = False

        self.user_input_color = user_input_color if pretty else None
        self.tool_output_color = tool_output_color if pretty else None
        self.tool_error_color = tool_error_color if pretty else None

        self.input = input
        self.output = output

        self.pretty = pretty
        if self.output:
            self.pretty = False

        self.yes = yes

        self.input_history_file = input_history_file
        if chat_history_file is not None:
            self.chat_history_file = Path(chat_history_file)
        else:
            self.chat_history_file = None

        self.encoding = encoding

        if pretty:
            self.console = Console()
        else:
            self.console = Console(force_terminal=False, no_color=True)

        current_time = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
        self.append_chat_history(f"\n# aider chat started at {current_time}\n\n")

    def read_text(self, filename):
        try:
            with open(filename, "r", encoding=self.encoding) as f:
                return f.read()
        except (FileNotFoundError, UnicodeError) as e:
            self.tool_error(str(e))
            return None
>>>>>>> UPDATED
```

Now, let's add the `--encoding` command-line switch to `aider/main.py`:

```python
aider/main.py
<<<<<<< ORIGINAL
    parser.add_argument(
        "--no-dirty-commits",
        action="store_false",
        dest="dirty_commits",
        help="Disable commits when repo is found dirty",
    )
    parser.add_argument(
        "--openai-api-key",
        metavar="OPENAI_API_KEY",
        help="Specify the OpenAI API key",
        env_var="OPENAI_API_KEY",
    )
    parser.add_argument(
        "--openai-api-base",
        metavar="OPENAI_API_BASE",
        default="https://api.openai.com/v1",
        help="Specify the OpenAI API base endpoint (default: https://api.openai.com/v1)",
    )
=======
    parser.add_argument(
        "--no-dirty-commits",
        action="store_false",
        dest="dirty_commits",
        help="Disable commits when repo is found dirty",
    )
    parser.add_argument(
        "--encoding",
        default="utf-8",
        help="Specify the encoding to use when reading files (default: utf-8)",
    )
    parser.add_argument(
        "--openai-api-key",
        metavar="OPENAI_API_KEY",
        help="Specify the OpenAI API key",
        env_var="OPENAI_API_KEY",
    )
    parser.add_argument(
        "--openai-api-base",
        metavar="OPENAI_API_BASE",
        default="https://api.openai.com/v1",
        help="Specify the OpenAI API base endpoint (default: https://api.openai.com/v1)",
    )
>>>>>>> UPDATED
```

These changes should implement the requested functionality. Please review and let me know if any further changes are needed.

aider/io.py

@@ -100,6 +100,7 @@ class InputOutput:
         user_input_color="blue",
         tool_output_color=None,
         tool_error_color="red",
+        encoding="utf-8",
     ):
         no_color = os.environ.get("NO_COLOR")
         if no_color is not None and no_color != "":
@@ -124,6 +125,8 @@ class InputOutput:
         else:
             self.chat_history_file = None
 
+        self.encoding = encoding
+
         if pretty:
             self.console = Console()
         else:
@@ -132,6 +135,14 @@ class InputOutput:
         current_time = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
         self.append_chat_history(f"\n# aider chat started at {current_time}\n\n")
 
+    def read_text(self, filename):
+        try:
+            with open(filename, "r", encoding=self.encoding) as f:
+                return f.read()
+        except (FileNotFoundError, UnicodeError) as e:
+            self.tool_error(str(e))
+            return None
+
     def get_input(self, root, rel_fnames, addable_rel_fnames, commands):
         if self.pretty:
             style = dict(style=self.user_input_color) if self.user_input_color else dict()

aider/main.py

@@ -185,6 +185,11 @@ def main(args=None, input=None, output=None):
         dest="dirty_commits",
         help="Disable commits when repo is found dirty",
     )
+    parser.add_argument(
+        "--encoding",
+        default="utf-8",
+        help="Specify the encoding to use when reading files (default: utf-8)",
+    )
     parser.add_argument(
         "--openai-api-key",
         metavar="OPENAI_API_KEY",