docs: improve Windows setup instructions for TextTest with Python

Fixes issue where newer versions of texttest produce .exe files instead of .py files. Updated start_texttest_from_python.bat to use texttestc.exe instead of texttestc.py. Also enhanced documentation for Windows users with recommendations for tools like Meld and fc.

start_texttest_from_python.bat

@@ -10,5 +10,5 @@ venv\Scripts\pip install texttest
 if %ERRORLEVEL% GEQ 1 (
     pause
 ) else (
-    venv\Scripts\texttestc.py -con %*
+    venv\Scripts\texttestc.exe -con %*
 )