feat: unhardcoded down get hit offset , yAccel fix

[potsmugen]

Feat:

• When a character is hit into the air while lying down, a Y offset of 15 (in 320x240 localcoord) is normally applied. This value can now be changed with the "movement.down.gethit.offset" constant

Fix:

• Fixed a couple Hitdef/GetHitVar defaults being inconsistent in widescreen