Double brackets using MW template format

[xZise]

The MW uses {{…}} for templates and {{:Bla}} is a valid name which shouldn't be considered a problem. One way to mitigate (at the moment) would be to use {{ :Bla}} because Python doesn't allow { }.format(42).

Another way would be to ignore constellations where there are an even number of brackets on each side as they aren't parsed but its number gets halved.

[xZise]

It may be possible to avoid this by adding an option to only check calls which use format, and not to use all strings. Also ca9b86f did alleviate that problem a bit as it now only checks fields discovered by Formatter.parse which will automatically exclude {{foo}}.

[jayvdb]

A similar problem occurring in MoinMoin
https://bitbucket.org/thomaswaldmann/moin-2.0/src/default/MoinMoin/converter/_tests/test_moinwiki_in.py?fileviewer=file-view-default#test_moinwiki_in.py-272 (which is a pytest project)