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.
Update NEWS
Merge branch 'sophist_fix_error_on_malformed_TRCK_tag' of git://github.com/Sophist-UK/picard into Sophist-UK-sophist_fix_error_on_malformed_TRCK_tag

Conflicts:
	NEWS.txt