[PATCH 0 of 5] [PATCH] convert: several additional filtering and mapping options

[Yury Sulsky]

Hi all,

This set of patches adds a couple of options to the "convert" extension.

  --includerevs/--excluderevs: list specific revisions you'd like to
    include in/exclude from the destination repo

  --descmap allows you to change commit messages

  --filemap takes an additional directive, "preprocess" that allows
    you to alter the converted files' contents

I took the opportunity to refactor filemap.py slightly: I copied
filemap.py to filtermap.py and removed everything other than the
filemapper class from the former.  In filtermap, I split
filemap_source into filtermap_base, which just handles the logic for
picking out a subset of revisions to convert, and filtermap_source,
which specifically supports including specific revisions and/or files.

How do these patches look? I tried to adhere to the coding guidelines
but I haven't contributed before so feedback is very welcome.

Thanks,
Yury