Rewrote horizontal momentum retention when entering platdrop:

• Removed ground friction during grounded platdrop frames (lasts 2F for most characters, 3F for Ken, Ryu, Terry)
  • Improves pre-adjustment platdrop momentum for everyone, especially high-friction characters
  • Ground friction is doubled if moving faster than the max walk speed, so this effectively removes 4F ground friction
• If entering platdrop with more than max horizontal air speed (air_speed_x_stable):
  • Multiply horizontal speed by the square root of the horizontal jump speed multiplier (jump_speed_x_mul)
  • Then clamp it to between max horizontal air speed and a multiplier* of the max horizontal air speed
    • *For Luigi, this multiplier is 2.65x. For everyone else, it's 1.7x, subject to future balance adjustments

In effect, these changes align platdrop momentum with the design of a characters aerial stats - characters intended to be mobile on the ground but slow in the air will no longer have wavedrops that sidestep their weakness in aerial stats. Generally wavedrop speeds are lower on average, but some high-friction characters have better wavedrops than before. The highest new wavedrop speeds are much lower than the highest old wavedrop speeds.