Convert docstrings to reStructuredText

This commit also includes:

  - whitespace / code formatting fixes
  - slight syntax related changes: except <exception_name>, e -> except <exception_name> as e
  - 3 pointless instructions instances have been rewritten [sorted] (spotted by semi-automatic check)

The unrelated changes shouldn't have any real impact on whipper's behaviour.

whipper/program/sox.py

@@ -8,11 +8,12 @@ SOX = 'sox'
 
 
 def peak_level(track_path):
-    """
-    Accepts a path to a sox-decodable audio file.
+    """Accept a path to a sox-decodable audio file.
 
-    Returns track peak level from sox ('maximum amplitude') as a float.
-    Returns None on error.
+    :param track_path: full path to audio track.
+    :type track_path: str
+    :returns: track peak level from sox ('maximum amplitude') or None on error.
+    :rtype: float or None
     """
     if not os.path.exists(track_path):
         logger.warning("SoX peak detection failed: file not found")