Docs: Math updates
Preserve face ordering in OBJLoader and OBJMTLLoader.

OBJ loaders did not correctly preserve vertex and face list ordering and were creating duplicate vertex entries, rather than letting faces share vertices.
Generalize PLYLoader to correctly handle ascii ply files with unrecognized components.

Now won’t give mangled results if the ply file is saved with colors or normals. Included is a test file that is saved with color and broke the old loader.
PLYLoader: Add support for color in ascii ply files.
PlyLoader: Added support for binary ply files.
Updated Vector4's setAxisAngleFromRotationMatrix and setAxisAngleFromQuaternion docs
OBJLoader & OBJMTLLoader: Fixed sharing of Vector2 & Vector3 objects by UVs & normals.

Should bring the OBJ(MTL)Loader into compliance with #3762.
OBJ{MTL}Loader: Formatting & whitespace fixes.
PLYLoader: Formatting & whitespace fixes.
More math doc updates
Merge branch 'documentation_updates4' into documentation_updates3
Merge remote-tracking branch 'upstream/dev' into documentation_updates3
Merge branch 'plyloader-improvements' of https://github.com/algrs/three.js into dev
Merge branch 'objloader-preserve-face-order' of https://github.com/algrs/three.js into dev
Merge branch 'dev' of https://github.com/mrdoob/three.js into dev
Link constants to the docs pages that list possible values