Reduce code redundancy using a generator
Move code generating py file name fro ui file name to its own function.
Add --files= option to setup.py build_ui, to pass list of files to rebuild

Related to http://tickets.musicbrainz.org/browse/PICARD-566
Add missing whitelines.
Allow compilation of ui files in unusual directories.

.py file will be produced in the same directory of the .ui file
Drop time-stamp comparison, remove variable comments from generated files.

See discussion at http://tickets.musicbrainz.org/browse/PICARD-566
Fix sub-menu capability for plugins...

1. xrange(x, y) goes from x to y-1. If len(MENU) is 1 this is never
called. So add 1 to get correct range.

2. Exception handling is typically slower and code is less clear than if
we just test for the key existing.
Minor style improvement
Show id3 version in info - resolves PICARD-218
Add NEWS
Tweak NEWS
Fix error on malformed TRCK tag.
Provide error log on invalid format.
Provide same checks for TPOS
Match TRCK and TPOS using regex and reduce code redundancy.
Use re named groups to match values and metadata keys.
Merge pull request #1 from zas/tpos_trck

@zas: Match TRCK and TPOS using regex and reduce code redundancy.

@sophist: I wondered whether this code was too difficult to read, but in the end decided it wasn't.
Get rid of 'if logdebug: logdebug(...)' pattern using a noop function

Suggested by @Mineo in https://github.com/musicbrainz/picard/pull/254/files#r11290500
Update NEWS
Fix instance where QStringList is now a list (post-fa66e9f)