ANGLE in Processing

[TeoJT]

Google ANGLE is a compatibility layer which translates OpenGL commands into modern APIs like Direct3D, Vulkan, and Metal.
This PR is an attempt to add ANGLE to Processing as part of efforts to move away from OpenGL and JOGL (#881)
GLFW is used as the windowing system, LWJGL used as a binding library to use OpenGL ES and GLFW.

Current state

Window launches with basic animation using background(), but cannot actually draw anything on to the screen due to a pointer issue. No OpenGL errors detected and runs without any warnings.

TODO:

• Fix issue where null pointer is passed in functions like glDrawElements() which causes nothing to render.
• GLFW keyboard and mouse input
• ANGLE libraries (libEGL.dll, libGLESv2.dll, vulkan-1.dll) to be exported with sketch in sketch working dir.
• more...