refactor<*>: rewrite all codes...

src/Commands/GetRepositoryRootPath.cs

@@ -0,0 +1,17 @@
+namespace SourceGit.Commands {
+    /// <summary>
+    ///     取得一个库的根路径
+    /// </summary>
+    public class GetRepositoryRootPath : Command {
+        public GetRepositoryRootPath(string path) {
+            Cwd = path;
+            Args = "rev-parse --show-toplevel";
+        }
+
+        public string Result() {
+            var rs = ReadToEnd().Output;
+            if (string.IsNullOrEmpty(rs)) return null;
+            return rs.Trim();
+        }
+    }
+}