WIP: indent: major rewrite

[blueyed]

• Use \v with all patterns.
• Align list entries properly, using a new function.
• New settings: indent_list_entries to allow extra indent for list entries (on by default).

This is pretty unclean currently, I am just glad to get it improved and working for now.

Tests for this would be useful! I suggest using https://github.com/junegunn/vader.vim. What do you think?

Fixes https://github.com/chase/vim-ansible-yaml/issues/35