subrepo: further replacement of try/except with 'next' Burn StopIteration, Burn!

parsers: use 'next' instead of try/except This get rid of another StopIteration abomination. The change in self.current value is supposed to not matter as nobody should be calling '_advance' after that (as per Matt wisdom).

dagparser: use 'next' instead of try/except for default value "Ich liebe es wenn ein Plan funktioniert."

getlogrevs: rewrite a loop to get read of try/except Get rid of the 'except StopIteration' abomination.

_makelogrevset: replace try/except with 'next' usage More readable without the 'except StopIteration' abomination.

ignore: move readpatternfile to match.py In preparation for adding 'include:' rule support to match.py, let's move the pattern file reader function to match.py

ignore: rename readignorefile to readpatternfile A future commit will move the readignorefile logic into match.py so it can be used from general match rules. Let's rename the function to represent this new behavior.