Generalized user string into variable in zshrc
In .xinitrc: moved wallpaper init to the back, as sometimes summons too large.
Also inserted parcellite initialization, for clipboard management.
In .zshrc: optimized reproot function to also detect repository directories with dashes, dots and underscores.
In .zshrc: rearranged aliases and optimized ct/gt command
to open a new urxvt window in the background with the same pwd.

Also added aliases for reboot and halt.
Don't forget to add the following line to your sudoers file for it to work without entering your password:
%wheel <user> =NOPASSWD: /sbin/shutdown -h now,/sbin/halt,/sbin/poweroff,/sbin/reboot

NOTE: the user is substituted in <user>
In .zshrc: Ruby Gem path is added to the
PATH env variable if Gem is installed.
As the version cannot be extracted from the `gem -v` command,
it must be added manually (now 1.9.1).
Added the vim system file .netrwhist to the IGNORE list.