Start improving code quality of NbtkTextureCache
Start improving code quality of NbtkTextureCache

This change starts to improve NbtkTextureCache in the following ways:

* Switches to using a GLib style typedef'ed struct
* Uses the slice allocator to allocate memory
* Fixes a security issue with the incorrect use of strcpy rather than strncpy
* Fixes a leak of a GError
* Fixes whitespace errors

clutter-project/mx,clutter-project/mx,pwithnall/mx,jonnylamb/mx,pwithnall/mx,jonnylamb/mx,jonnylamb/mx,pwithnall/mx,jonnylamb/mx,clutter-project/mx,pwithnall/mx,clutter-project/mx