project: reorganize the structure of the project.

* remove dotnet-tool.json because the project does not rely on any dotnet tools.
* remove Directory.Build.props because the solution has only one project.
* move src/SourceGit to src. It's not needed to put all sources into a subfolder of src since there's only one project.

src/Models/Change.cs

@@ -0,0 +1,75 @@
+using System;
+
+namespace SourceGit.Models
+{
+    public enum ChangeViewMode
+    {
+        List,
+        Grid,
+        Tree,
+    }
+
+    public enum ChangeState
+    {
+        None,
+        Modified,
+        Added,
+        Deleted,
+        Renamed,
+        Copied,
+        Unmerged,
+        Untracked
+    }
+
+    public class Change
+    {
+        public ChangeState Index { get; set; }
+        public ChangeState WorkTree { get; set; } = ChangeState.None;
+        public string Path { get; set; } = "";
+        public string OriginalPath { get; set; } = "";
+
+        public bool IsConflit
+        {
+            get
+            {
+                if (Index == ChangeState.Unmerged || WorkTree == ChangeState.Unmerged)
+                    return true;
+                if (Index == ChangeState.Added && WorkTree == ChangeState.Added)
+                    return true;
+                if (Index == ChangeState.Deleted && WorkTree == ChangeState.Deleted)
+                    return true;
+                return false;
+            }
+        }
+
+        public void Set(ChangeState index, ChangeState workTree = ChangeState.None)
+        {
+            Index = index;
+            WorkTree = workTree;
+
+            if (index == ChangeState.Renamed || workTree == ChangeState.Renamed)
+            {
+                var idx = Path.IndexOf('\t', StringComparison.Ordinal);
+                if (idx >= 0)
+                {
+                    OriginalPath = Path.Substring(0, idx);
+                    Path = Path.Substring(idx + 1);
+                }
+                else
+                {
+                    idx = Path.IndexOf(" -> ", StringComparison.Ordinal);
+                    if (idx > 0)
+                    {
+                        OriginalPath = Path.Substring(0, idx);
+                        Path = Path.Substring(idx + 4);
+                    }
+                }
+            }
+
+            if (Path[0] == '"')
+                Path = Path.Substring(1, Path.Length - 2);
+            if (!string.IsNullOrEmpty(OriginalPath) && OriginalPath[0] == '"')
+                OriginalPath = OriginalPath.Substring(1, OriginalPath.Length - 2);
+        }
+    }
+}