Added general usage information. Made sure gitignore api is never called
without any arguments.
Made script fzf aware -- if it finds fzf it can be invoked without
arguments, if it does not it will display usage information instead.
The only file left in $HOME is .zshenv, which sets up zsh to source everything from XDG_CONFIG_HOME/zsh.
Shell files are split into sh and zsh directories, for global assignments (which should be posix compliant, work on any posix shell) like environemnt variables, xdg vars, and global aliases. zsh contains zsh specific customization (prompt customization, plugin loading, zsh completions).
Zsh initialization will pull from sh directory first, loading the respective mirror to its startup file (`.zprofile` loads `sh/profile` and `profile.d/*`, `.zshenv` loads `sh/env` and `sh/env.d/*` and `zsh/env.d/*`, `.zshrc` loads `sh/alias`, `sh/alias.d/*` and `zsh/alias.d/*`)
Once all is done, it will have loaded both global variables, aliases and settings, and zsh-only specifications. Other stow modules, if they want to add shell functionality, can include their aliases and functions in one of the above directories to automatically be picked up by zsh.
Added global git config file, following XDG specifications (putting it
under `XDG_CONFIG_HOME/git/config`).
Adding a small improvement to default dot session for tmux, so that its
log watcher now shows all refs and remote refs.
