.makepkg.i686.conf: add multilib config for Arch Linux
.vimrc: tweak configuration

Copy things from:
* https://github.com/maggick/dotfiles/blob/master/vimrc
* https://github.com/rafaelcaricio/dotfiles/blob/master/vim/.vimrc
* https://github.com/eduardolundgren/dotfiles/blob/master/templates/.vimrc
.shell/aliases: add sqlite3dump alias