Emit warning when the subcode's pre-emphasis flag of a track differs from the ToC's one

In the future I'd like to make sure this information is included in the logfile too (maybe also in the cue sheet).

Related to issue #296.

Signed-off-by: JoeLametta <JoeLametta@users.noreply.github.com>

whipper/program/cdrdao.py

@@ -22,6 +22,8 @@ _BEGIN_CDRDAO_RE = re.compile(r"-" * 60)
 _LAST_TRACK_RE = re.compile(r"^[ ]?(?P<track>[0-9]*)")
 _LEADOUT_RE = re.compile(
     r"^Leadout AUDIO\s*[0-9]\s*[0-9]*:[0-9]*:[0-9]*\([0-9]*\)")
+_SUBCODE_EMPHASIS_LINE = ("Pre-emphasis flag of track differs from TOC - "
+                          "toc file contains TOC setting.")
 
 
 class ProgressParser:
@@ -55,6 +57,10 @@ class ProgressParser:
                   "found %d Q sub-channels with CRC errors" %
                   (self.currentTrack, int(crc_s.group('channels'))))
 
+        # TODO: add subcode pre-emphasis info for each track to logger too
+        if _SUBCODE_EMPHASIS_LINE in line:
+            logger.warning(_SUBCODE_EMPHASIS_LINE)
+
         self.oldline = line