Physics: Restore shape loading in createBody

Previously it created testing shape instead of real one, because of a bug
with no collision. I can no longer replicate this bug, so I restored old
code.
Physics: Fix cylinder shape's height

Bullet uses half-extents, and I use full numbers, so I divide those by 2
during shape creation. Just now I noticed that cylinder's height adjustment was
commented out -- no idea why I commented that line. Now fixed.