Merge branch 'next'

* next:
  fix visual selection mappings
  fix <C-n> issue with mapping_wrapper()
  update and reformat docs for mappings
  limit some mapping to work only within some sections
  move folding wrapper function into magit/mapping.vim
  move helper functions in autoload/helper.vim
  only set autocmd once for write command checking
  cut info lines to remove tail spaces
  do not use printf("%S"), not supported by vim 7.3
  forward travis status to gitter