#7 test multiple uvs

now should have access to more than 2 uvs in godot. pretty sure needs to be exported with blender 2.8 or > and gltf.

build a test project to see what works.

gltf works from blender 3.0:

varying vec2 uv3;
varying vec2 uv4;
varying vec2 uv5;
varying vec2 uv6;

uv3 = vec2(CUSTOM0[0], CUSTOM0[1]);
uv4 = vec2(CUSTOM0[2], CUSTOM0[3]);
uv5 = vec2(CUSTOM1[0], CUSTOM1[1]);
uv6 = vec2(CUSTOM1[2], CUSTOM1[3]);

dae from upbge does not work.