Code to support icons which are shown with an "incorporated" bar indicating the pps...

Code to support icons which are shown with an "incorporated" bar indicating the pps percentage.
Add a set of dom icons, I hope I did something decent... surely as they are they don't fit luminos' style so I've put them only in the nexuiz skin.

Rename hud_panel_modicons_dom_pps to hud_panel_modicons_dom_layout and add it to defaultXonotic.cfg
3 possible layouts:
0) only icons
1) icons and percentage of average pps (points per second)
2) icons and average pps

The whole code is now cleaner.