refactor<*>: rewrite all codes...

src/Commands/Add.cs

@@ -0,0 +1,27 @@
+using System.Collections.Generic;
+using System.Text;
+
+namespace SourceGit.Commands {
+    /// <summary>
+    ///     `git add`命令
+    /// </summary>
+    public class Add : Command {
+        public Add(string repo) {
+            Cwd = repo;
+            Args = "add .";
+        }
+
+        public Add(string repo, List<string> paths) {
+            StringBuilder builder = new StringBuilder();
+            builder.Append("add --");
+            foreach (var p in paths) {
+                builder.Append(" \"");
+                builder.Append(p);
+                builder.Append("\"");
+            }
+
+            Cwd = repo;
+            Args = builder.ToString();
+        }
+    }
+}