Math: fix compilation of tests with OpenGL ES.

Double precision is not supported there, mention that for skipped test
cases.
No need to use Double type in tests so extensively.

Makes porting to OpenGL ES easier.
Various other compilation fixes for OpenGL ES target.
Math: fixed test for denormalize<UnsignedLong, long double>().

Amazing what single forgotten literal can do.
DebugTools: no need to prefix the test so much.