Giving xp to defense sentinels for shooting projectiles

I have submitted changes to cvs so that defense sentinels will get a small amount of xp for shooting out projectiles. See this thread

Default value is 0.066 xp per projectile, so absolute max for one defense sentinel for 30 min map is 300, typical value would be 60-100.
This is well less than what an offensive sentinel could achieve.

Purpose is to encourage Engineers to use team-friendly defense sentinels rather than offensive sentinels.