Revert "-Fix: rewrote the movement code a bit again"

This reverts commit 32df764cb2a16d13d073ab0f05c0ce400f816285.
Revert "-Fix: I broke foot animation, oops (tnx wangds)"

This reverts commit 88af03ba0e49723cb7d060e3a553f5d3c8b0bc87.
Revert "-Fix: moving of units was kinda messy between gameSpeeds. This hopefully resolves it."

This reverts commit f125285489a34e967f3fc265308ea38d6d9dbbba.
-Fix: don't always round down (patch by wangds)
-Fix: airunits should be uneffected by gamespeed

By premature converting to and from gamespeeds, precision was lost,
resulting in different speeds for air units.
Also, it could adjust for speed twice, instead of once.

PS: this fixes sonic blasts reaching different distances on different
gamespeeds
-Fix: rounding lead to asymmetries when moving up/left vs down/right (based