* Changed the way experience for the speed stat is accumulated.

* See http://ufoai.org/wiki/Proposals/Stats,_Experience_and_Mission_Count_in_2.5-dev#Speed
* Adjusted max experience per mission gain.
* Moved max stat experience capping to client side.
* Adjusted auto mission experience gain.

* See bug #4861.
* Use Com_DPrintf.
* Use cgame api function pointer.