Updates skybox demo to show how to do both HDR and non HDR skyboxes

Co-authored-by: Jeffery Myers <JefMyers@blizzard.com>

* Fixing typecast warnings generated by visual studio 2019 in examples.

* Changes to fixes based on feedback

Co-authored-by: Jeffery Myers <JefMyers@blizzard.com>

Mostly typecasts, and some int to unsigned short changes, and including the windsock 2 library in the examples.

Co-authored-by: Jeffery Myers <JefMyers@blizzard.com>

REMOVED: core_basic_window.cpp

This is to account for GLTF info being more like instructions on how to build your animation instead of verbose description of each pose.

Co-authored-by: Jeffery Myers <JefMyers@blizzard.com>

* Added example for gltf animation and split some functions for loading model animations into IQM and GLTF similar to how models are being loaded.

* Removed wrongly duplicated function

* Bone loading for gltf model (not working at this point)

* Loading info about vertex to joint connection but animation is still not working

* Skeleton and pose is correctly loaded. Need to communicate about interpolation in GLTF

* The model almost looks like a real person on animation.

* Fixed model loading with bones.

Also updated license info on the model.

* Cleaned up some code and updated examples.

* Fix identation issues

* Fix identation issues

* Fix identation issues

* Documenting the compiler flags

* Moved some android compiler flags and added documentation on them too.

* Some more restructuring.

Removed unnecessary comments that were self described by the code.
Added some more explanations around certain parts of CMake and especially around compiler flags.

* Delete emscripten.cmake

This file is not needed at this point. EMSDK provides a toolchain file that has a lot more things in it and is better supported. Project currently works fine with the documentation provided in Emscripten SDK on how to build projects.

* First pass file separation.

The main two files are cleaner now. Only important things can be seen. Major changes include:
- raylib_static is now the alias instead of raylib
- Repeating segments are removed and pulled into separate files into <root>/cmake
- File is reordered to make more sense
- Installs are better structured
- Library is build into an output directory "raylib" instead of "src"
- All public header files are now set as a public header file
- Source files need to be listed (it is a bad practice to capture them using wildcards and file globs)
- CMakeLists are better commented

* Second pass on the example dirs.

They are quite complex so I'm more hesitant to do major changes. Also it works pretty well. Noticed that I forgot one of the seperated files and added it into src/CMakeLists.txt.

* Returned the header copy as it was convenient to have the public headers copied.

* A better description to the variable RAYLIB_IS_MAIN

Co-authored-by: Rob Loach <robloach@gmail.com>

* Remove debug message

Co-authored-by: Rob Loach <robloach@gmail.com>

* Improvements based on review.

* Simplify the install condition to not be platform specific as it was before.

Co-authored-by: Alexander Neumann <30894796+Neumann-A@users.noreply.github.com>

* Remove some CMAKE variables as they don't affect the build in any way

Co-authored-by: Alexander Neumann <30894796+Neumann-A@users.noreply.github.com>

Co-authored-by: Rob Loach <robloach@gmail.com>
Co-authored-by: Alexander Neumann <30894796+Neumann-A@users.noreply.github.com>

Co-authored-by: funcelot <artur.mustafin@gmail.com>

Previous GetKeyPressed() method was actually returning unicode codepoints equivalent values instead of the key-code of the pressed key. So, it has been replaced by GetCharPressed(), returning unicode codepoints and GetKeyPressed() now returns key-codes.

* Fixed the build for web using CMake.

I found that the build for me was failing and I added some if defined checks in the core.c file where the glfwSetWindowAttrib was used. (error: implicit declaration of function 'glfwSetWindowAttrib' is invalid in C99 [-Werror,-Wimplicit-function-declaration])

I also changed some values in the toolchain file so that it correctly uses the .bat files when on windows.

* Cleaned up the additional variables (they are not important)

* Added more improvements to cmakelists

Added the option to use the system provided Emscripten toolchain to be more uniform with other libraries.

Fixed and issue which prevented example being built from cmake and also building with html extensions properly.

* Fixed ENUM to STRING because of a missed warning

* Fixed #1455

Fixed writing out of array bounds
Adjusted FPS comment to match value
Deleted unused function at the end, which has never been in use in the history of this file

* Fixed #1455

Readded the function

Without GLFW_OPENGL_FORWARD_COMPAT, running this as a standalone will yield the error:
```
NSGL: The targeted version of macOS only supports forward-compatible core profile contexts for OpenGL 3.2 and above
```

Stumbled on this example and I love this! Adding instructions that work for me on MacOS.. Note that glfw3 will need to be statically built locally and copied to this external/libs directory on mac. I can upload my static version, but it probably makes sense to do this only if there's some general naming convention for adding platform specific folders. Like "external_osx/lib" or "external/lib_osx". Then I'll drop my static libs in there.

WARNING: Several functions removed, replaced by SetWindowState() / ClearWindowState() equivalents, only for advance users.
ADDED: ClearWindowState() to reset window state
REMOVED: HideWindow() / UnhideWindow()
REMOVED: DecorateWindow() / UndecorateWindow()