Optimizations to the code that monitors and reloads images if they change NON WORKING
Fixes segmentation fault at line 353 in tileset.cpp caused by mTiles equalling null
Fixes second segmentation fault caused by use of qDeleteAll
Changes tileset.cpp and tileset.h to try and address the problem of dfferent sized tilesets. However, it currently encounters a segmentation fault at line 231 of tilesetmanager.cpp
Fixes segmentation fault caused by destroying variables at the end of line 220 of tilesetmanager.cpp which resulted in pointers pointing to garbage.
Fully implements optimisations to reloading multiples of the same images - #825
Cleanup and additional comments