Pmove retardedness

[jdolan]

• Can jump up to 80 units high when holding +forward
• Player does not clip against walls smoothly, loses too much velocity
• Player can get wedged against walls on stairs, which results in rapid view origin shaking
• Game module detects falling too easily and initiates jump / fall animation too eagerly

[jdolan]

r1520:1530 were committed against this. Much of Quake3's pmove logic and flow have been merged in.

• The uber-jump happening in certain corners has been fixed.
• Players now step down stairs instead of falling down them. This looks much better and eliminates a lot of animation state thrashing on stairs.
• Lots of work on water exit and water movement, with realistic friction depending on water depth.
• Relaxed velocity clamp and air friction to more closely resemble Quake2 feel.
• Quake2 double jumps are back!

There are still some minor bugs and tuning required, but this should get us into beta.