- Don't use BGRA format at all. It doesn't work with non-typical cases (i.e. with srgb or compressed textures) and also casues artifacts on some android devices. I kept the extension in central settings, but it probably won't be used.
- Use sRGB texture format when advanced lighting is enabled. This makes it closer to the original OpenGL renderer and also avoids to have even more #ifdef's for sRGB conversions.
- Keep RGBA textures for non-advanced lighting to make it simpler.
Now advanced lighting in GLES looks almost the same as in OpenGL 3.x (without shadows/GI)
For OpenGL 3.x renderer it only matters for some buggy drivers (i.e old AMD driver that complains about missing precision qualifier). Based on specification is should have no effect and was added for compatibility with GL ES.
In our case vertex and fragment must have the same precision because we use common header for both shader types and the precision for uniform variables must match.
Also "precision highp float;" is defined by default for both vertex and fragment shaders, so it seems to be more proper.
This will hopefully solve the problem with nvidia driver that tries to use f16vec4 instead of just vec4, see:
https://forum.freegamedev.net/viewtopic.php?f=17&t=7397&sid=06682ddb05ee9fbf48a2984d0bd48d5b
It allows to enable it easily in GLES renderer. And we check if this extension is available anyway because it's needed for shadows, so we can use it for other shaders too.
