Useful to enable additive blend mode for particles

Requires raymath as standalone and GLEW

...shader loading security check

Added window drop files support

Now gestures system can be used as standalone module

Camera system can be used as standalone module

Now audio module can be used as standalone module

Shader functionality owns to rlgl, not core module

Added:
- LoadImageRaw()
- ImageCopy()
Renamed:
- GetPixelData() -> GetImageData()

Now it supports multiple maps one next to the other

Corrected issues with textures loading

Corrected shader version depending on OGL version
Corrected bug in gestures module