[Feature Request] Add Sub-directory Scanning

This is a feature request to add sub-directory scanning inside folders, as currently this is not implemented.

e.g

--[Textures]
  hills.dds
  grass.dds
  --[Armor]
    boots.tga
    helmet.tga

Currently, if you select the "Textures" folder, the program will only list hills.dds and grass.dds. boots.tga and helmet.tga will not show up as they are in the sub-directory "Armor", and Sub-directories are not being detected.