Fixed i3bar rendering and implemented inset windows in i3
Added window inset config option and command

This patch adds:
    'new_window inset <number>'
    'new_float  inset <number>'

and the command:
    'inset <number>'

Ex.
new_float inset 4
bindsym $mod+h inset 2
Added enable_alpha_channel option

This enables true 32-bit alpha support for i3 ( This is mainly nessisary
for the inset window's patch, as it fixes issues with graphical
glitches)

To use, put this:
enable_alpha_channel yes

in your config file