Make the integral versions of irr::core::equals() do a direct == comparison when no explicit tolerance is specified, rather than using an implicit tolerance of 0.  The floating point versions are unchanged. New unit test added.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@1999 dfc29bdd-3216-0410-991c-e03cc46cb475