fix mapgen of other scripts too
fix stereoscopic rendering leading to screen "running away to the left" since webgl merge (due to bug in webgl branch). reason was incomplete change of name/scope of variable stereoDepth -> cStereoDepth
also fix top/bottom and side-by-side rendering (got also broken in webgl branch)
simplify {$IF that pas2c did not seem to understand
another small rendering tweak/fix