Fixed the missing Windows API check for _WIN32 and _WIN64, both in trunk and 1.4. Finished the API enhancements in quaternion and vector classes. All methods now return the object where necessary.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@1297 dfc29bdd-3216-0410-991c-e03cc46cb475