Bug #1526176 - use absolute path names when creating / finding textures.  As a consequence, createAndOpenFile() also needs to use absolute path names in order to match the texture filenames.  Tested on Win32 with all example apps and a small test app attached to the bug.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@1673 dfc29bdd-3216-0410-991c-e03cc46cb475