The html reporter was lately a second class citizen in Pylint,
being underdeveloped and mostly neglected. It has a couple of bugs,
but the more important reason why this is removed is that we now have
a much better json reporter, which can be used as a basis for more
prettier html Pylint outputs.
Part of #975
Changed the documentation in couple of places, merged sections together,
described testing procedures and added more up-to-date information
in general.
This changeset introduces a reporters.Message class to represent
messages with their attached data. Those messages object can then
be formatted accordingto some template.
A template can be specified on the command line through the
msg-template option.
This deprecates parseable and msvc output format, and kill --symbols
and --include-ids option.
