Add option g:indent_guides_default_mapping
Merge branch 'option-no-mapping' of git://github.com/suy/vim-indent-guides into suy-option-no-mapping

* 'option-no-mapping' of git://github.com/suy/vim-indent-guides:
  Add option g:indent_guides_default_mapping

Conflicts:
	plugin/indent_guides.vim
Update the help file for the g:indent_guides_default_mapping option