Rework long-lines plugin to use colorcolumn

This will always highlight characters that exceed the 80 character
limit with ErrorMsg, but will also highlight the 81st column, so
the user knows when to break.
Fix { keymap in match-brackets.vim

The { mapping used to open a C-style block, however, it gave several
problems when dealing with Perl code and hashes. This converts it to
simply working as {}, like the ( -> () and [ -> [] mappings.