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.

ignore: combine readignorefile and _ignorefile _ignorefile did nothing except open the file. Let's combine it with readignorefile for simplicity. This will make it easier to rename and move to match.py in upcoming patches.

ignore: move bad file handling out of readignorefile In preparation for moving readignorefile to match.py to make it more generally usable, let's move the bad ignore file handling up to the ignore specific logic.

ignore: remove .hgignore from ignore list if nonexistent Previously we would always pass the root .hgignore path to the ignore parser. The parser then had to be aware that the first path was special, and not warn if it didn't exist. In preparation for making the ignore file parser more generically usable, let's make the parse logic not aware of this special case, and instead just not pass the root .hgignore in if it doesn't exist.