This uses a similar multipass approach to blend shapes
as Godot 3.x, the major difference here is that we
need to convert the normals and tangents to octahedral
for rendering.
Skeletons work the same as the Vulkan renderer except the bones
are stored in a texture as they were in 3.x.
This includes collision (2D SDF, Box, Sphere, Heightmap),
attraction (Box, Sphere), and all sorting modes.
This does not include 3D SDF collisions, trails, or
manual emission.
This allows using texture_2d_get on all platforms which is needed for the get_image function
This commit also fixes some OpenGL warnings on the Web platform that came from attempting to map a buffer with zero length
* Map is unnecessary and inefficient in almost every case.
* Replaced by the new HashMap.
* Renamed Map to RBMap and Set to RBSet for cases that still make sense
(order matters) but use is discouraged.
There were very few cases where replacing by HashMap was undesired because
keeping the key order was intended.
I tried to keep those (as RBMap) as much as possible, but might have missed
some. Review appreciated!
