[Open Assets] 10-Line Momentum 6-Line-Momentum V1.1

Just 2 simple changes
Changed player.speed into FixedHypot(player.mo.momx, player.mo.momy)
for normal people, that means it should be a little more consistent hopefully
and made the point where momentum kicks in scale with size.

Due to some help from @Kinda Bobby, he told me some things I can do to get the code even shorter. Thanks a lot to him!

Just shortened the code into 9 lines