xinitrc: start trayer via `trayer-restart`

Signed-off-by: Niklas Koep <niklas.koep@gmail.com>
zshrc: add `lan` and `wifi` alias for wicd-cli

Signed-off-by: Niklas Koep <niklas.koep@gmail.com>
xmonad: add volume control keybindings

Signed-off-by: Niklas Koep <niklas.koep@gmail.com>