FBX files may use a texture reference from an embedded texture that hasn't been loaded yet. This patch fixes this issue, storing all texture filenames, that can be acessed later via "scene::GetEmbeddedTexture", when all textures are already loaded.
Some warnings have been added to other file formats that uses embedded data.
Fixed a bug where FBX loader won´t load embedded textures that don´t have the Content data filled. Some FBX files only fill this data once, so any embedded texture with the same source filename, should use the pre-loaded data.
Fixed another bug where FBX Texture "Filename" field came different than on some files than the one defined by the code. One suggestion is load all properties by the case-insensitive function created.
Added the "AI_CONFIG_IMPORT_FBX_SEARCH_EMBEDDED_TEXTURES" flag to tell the importer to load embedded texture data from already loaded ones.
(keep the previous method for "allMaterials" option, this should be change too since the materials indexes used are not the good ones, or just remove the object / material test
