Don't override customized environments in subshells

Only set up environment for the top-level shell, and allow it to be
inherited normally.

See: https://github.com/sorin-ionescu/prezto/pull/500
Update zpretorc to match latest runcom
Improve autostart so it can load more extensions
rcrc: move to now that RCM was updated
rcrc: Clean up file
Start using XDG_CONFIG directories
zsh: Set XDG variable for RCM (rcrc)
zsh: move zshenv to config directory
zsh: refactor and move everything into $XDG_CONFIG_HOME
zsh: move my zsh settings out of it now useless dedicated directory
zsh: remove/replace references to the old zsh.d directory
Fix link in readme for rcm
xinitrc: move autostart to config
XDG_CONFIG_HOME doesnt exist yet
zsh: improve readability of after/path file
zsh: change b (browser) prezto alias to br
zsh: add nodejs and tmuxifier confs
Add pentadactylrc