add skeletal animation to cmake and fix errors

[baptx]

The skeletal animation was not added to cmake for compilation and there were several errors to fix to compile successfully.

[baptx]

When I execute the compiled example 8.guest__skeletal_animation, there is an error:

ERROR::SHADER::FILE_NOT_SUCCESFULLY_READ
ERROR::SHADER_COMPILATION_ERROR of type: VERTEX
0:1(1): error: syntax error, unexpected $end

 -- --------------------------------------------------- -- 
ERROR::SHADER_COMPILATION_ERROR of type: FRAGMENT
0:1(1): error: syntax error, unexpected $end

 -- --------------------------------------------------- -- 
ERROR::PROGRAM_LINKING_ERROR of type: PROGRAM
error: linking with uncompiled/unspecialized shadererror: linking with uncompiled/unspecialized shader
 -- --------------------------------------------------- -- 
Segmentation fault (core dumped)

Any idea why?

Update: I fixed most issues by using the vertex shader file from https://learnopengl.com/Guest-Articles/2020/Skeletal-Animation, copying the fragment shader file from the example 3.model_loading__1.model_loading and adding them to the src directory of the new example by using the names written in the source code (anim_model_vs.glsl and anim_model_fs.glsl). I also added the line "src/${CHAPTER}/${DEMO}/*.glsl" in the file CMakeLists.txt below the 2 lines "src/${CHAPTER}/${DEMO}/*.gs". However there is still a segfault and I can see this error message:

ERROR::SHADER_COMPILATION_ERROR of type: VERTEX
0:1(10): error: GLSL 4.30 is not supported. Supported versions are: 1.10, 1.20, 1.30, 1.40, 1.50, 3.30, 4.00, 4.10, 4.20, 1.00 ES, and 3.00 ES

 -- --------------------------------------------------- -- 
ERROR::PROGRAM_LINKING_ERROR of type: PROGRAM
error: linking with uncompiled/unspecialized shader
 -- --------------------------------------------------- -- 
Segmentation fault (core dumped)

Is it possible to make it work with a version of GLSL lower than 4.30? I changed the version to 3.30, fixed some variables errors (using finalBonesMatrices instead of finalBoneMatrices and MAX_BONES instead of MAX_JOINTS) and also added missing parts from the tutorial but there is still a segfault.

For the example 3.model_loading__1.model_loading there was an issue assimp/assimp#2754 recently and I was able to fix it by removing the includes/assimp directory. To compile the latest version of LearnOpenGL repository, I only needed to keep some files in this directory: quaternion.h, vector3.h and matrix4x4.h.