Load game's user font file (.pgf) from game's image.

Loading pgf font files firstly from game's image, then from other origin paths. 
Especially support some chinese psp games which use their own fonts zh_gb.pgf from image.
(i.e., Do not need to do as before as : extracting that font file from image, then copy it into flash0\font\ folder as jpn0.pgf file.)