We urxvt now!

- I've found out how to copy, paste and use the scroll wheel on it.
  Edited README, Xresources, i3/config to reflect this change.
- i3/conkyrc: just battery_short will suffice
- xinitrc: merge Xresources on init, pick i3 as our WM
- zshenv: xdg-mime is smart enough to figure out what browser to use