Change ilLoadImage to guess filetype when load fails.
Change ilLoadImage to guess filetype when load fails.

This makes it possible to load an images when the file extentions doesn't match the type.

Change-Id: I57e51773662085da786d0dbf17cf1ac3fc48967e
Reviewed-on: http://10.236.89.5:8080/3213
Reviewed-by: Henrik Roslund <e8caef7a9dd093a023b212715d73af6d746b7206@Mecel.se>
Scrum-Card: Anders Arnholm <119bbdff62cc7cf6bb8c597c367940702727c3af@mecel.se>
Reviewed-by: Anders Arnholm <119bbdff62cc7cf6bb8c597c367940702727c3af@mecel.se>
Tested-by: Anders Arnholm <119bbdff62cc7cf6bb8c597c367940702727c3af@mecel.se>

balp/DevIL,balp/DevIL,balp/DevIL,balp/DevIL,balp/DevIL