Changed copyright end year to 2020 in every reference "Copyright (c) 2006-XXXX, assimp team".
Changed copyright end year to 2020 in every reference "Copyright (c) 2006-XXXX, ASSIMP Development Team".
Changed copyright end year to 2020 in LICENCE.rtf.
Changed copyright end year in CMakeFiles.txt files and any other places referencing Assimp with a copyright start and end year.
Added code to use Half-Life 1 MDL loader in MDLLoader.cpp.
Added Half-Life 1 MDL loader files to CMakeLists.
Added new options in config.h to use with Half-Life 1 MDL loader.
Some are doxy comments, some are just trivial source comment typos.
Found using `codespell -q 3 --skip="./contrib" -I ../assimp-whitelist.txt`
whereby whitelist contained:
```
childs
iff
lod
nto
ot
whitespaces
```
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.