uint to size_t for portability.

Signed-off-by: Khral Steelforge <garuda2550@gmail.com>
Move WebP reader to it's own function.

Signed-off-by: Khral Steelforge <garuda2550@gmail.com>
Fix memory leak on reading WebP files.

Signed-off-by: Khral Steelforge <garuda2550@gmail.com>
Merge branch 'gw2formats'