Add missing irrCoreEquals.cpp test file.  Update changes.txt to note that position2d is now a synonym for vector2d.  Add proper doxygen \deprecated tags for position2d.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@2001 dfc29bdd-3216-0410-991c-e03cc46cb475