Merge from 1.7 branch, revisions 3877-3908. Fix for getSphericalCoordinateAngles, some warnign fixes, md2 normal fix, several GUI fixes, isPointInside fix, zip endianess fix.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@3909 dfc29bdd-3216-0410-991c-e03cc46cb475