.bashrc: add $HOME/bin to PATH.
brew_setup: install Emacs as a GUI application.
brew_setup: test if symlinks exist, not files.
.bashrc: add $HOME/.cabal/bin to PATH.
osx_setup: SSD-specific tweaks.
osx_setup: more tweaks to Mail.app.
osx_setup: initial Messages.app configuration.
.gitconfig: fix the help.autocorrect setting.
.bashrc: source $HOME/.local if it exists.
osx_setup: remove Dropbox’s green checkmark icons in Finder.
brew_cask_setup: install native apps through brew-cask.
.bashrc: link Homebrew casks in `/Applications` rather than `~/Applications`.
brew_setup: simplify code.
osx_setup: add settings for Transmission.app.