Fix typo.
Fix particle shader.

Partially revert r12350. Thanks goes to Philip`.
Use latest XML2 version.
On Android use vswprintf_s, because we need to tweak the format.
Say hello to apitrace for 0 A.D.

Apitrace can be used to trace GL call on Android.
To enable it add "CONFIG+=apitrace" to qmake parameters.
Allow lobby & multiplayer on Android
Add scaleRatio variable.

This variable is needed to scale up the GUI. It's just a temporary
solution until GUI will support DPI.