Fix bug with nested RCS.

In case there is more than one RCS that can handle a given file, for
example a git repo, and inside it mercurial repo, and inside the file to
be committed, then choose the closest one to to the file (shortest
relative path).

Closes bug 2062
Sort by path length

Might be safer and/or clearer.
Fix for bug 1979 (new round)

[ci skip]
Add a very basic JSON page
Add remove_untranslated to po2mozlang

This allows it to work correctly when called from po2moz
Same names for test, doubt either has been run
Don't drop units with blank source, consider them always translated
Drop fuzzy units with remove_untranslated
Make this script work again
Keep parsed files for reuse
Add support for parsing placeables
Clean temporary files
Add command line parsing

Now accepts options to control what to benchmark, and can use existing
PO files as well.
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