Update vimrc: add 'qf' filetype to 'VariousFileTypes'
Update vimrc: remove 'gitcommit' file type from 'formatoptions+=ta'
Update vimrc: reorder some options
Update vimrc: remove unnecessary function
Update vimrc: add 'ack.vim' plugin
Update vimrc: add 'vim-qargs' plugin
Update vimrc: add 'AckReplace' command
Update vimrc: add 'AckReplace' function