Deal with failed LoadMusicStream

It would be good to have a way to continue execution even when loading a stream didn't work.
 Free music and set it to NULL in case something went wrong, so that users can check for it.

Complete raw_audio_stream example

Update Builder example

Update Builder example for raylib 2.0.0.
External OpenAL and GLFW are not required anymore.

1. Always synthesize a complete frame of audio, using a second buffer (this prevents gaps in playback)
2. Sine is computed correctly, with an adjustable frequency
3. User can modulate frequency in real-time with mouse
4. Entire audio buffer data is shown, visually demonstrating how sine changes in wavelength

Fix rlgl.h to be used as a standalone

Closes #588.

Mimic the Makefile by outputting html + js instead of LLVM IR.

Still a work in progress but it already works...
Current riqm API could be simplified...

Fixes: 1d0ba96 ("Add GLFW-installed-but-using-our-GLFW-anyway configuration")

as well as -DUSE_EXTERNAL_GLFW.

Nips issues like #584 in the bud.

Remove period after exclamation

Fixes https://www.reddit.com/r/gamedev/comments/90z6fy/raylib_20_released/e2v5qpl/ :)

Convert window render sizes to floats

GLSL 1.10 is typesafe ([PDF specs](https://www.khronos.org/registry/OpenGL/specs/gl/GLSLangSpec.1.10.pdf), page 22), so this shader will not load properly during build.

It's not a super important change, but I came across it while playing with the examples on my pi.

Examples can be compiled for web with no code change at all! Usually
examples need to be refactored for web... using emscripten code
interpreter (emterpreter), it can manage synchronous while() loops
internally... as a downside, execution is very slow...

Not properly configured, use VS2015.UWP as reference

Now it works with mini_al library

No model available, this example should probably be redesigned...

Oculus API has changed so much that it has no sense to keep this example here... it was funny to test it in the past...

This change allows rlgl.h usage as independent single-file header-only module... still some tweaks required, like removing GLAD dependency... required extensions could be manually loaded!

Also removed shader_distortion.h, embedded in rlgl.h