The node will mix various other types (not just int/float) hence the name change.

Add various types to the MixInput node + new features & update UI

- add new types to mix: Vectors, Colors, Quaternions and Matrices.
- add SWAP feature to let the input A & B be swapped
- add MIRROR feature to mirror the interpolation factor
- add custom icon to MixInputs node
- relocate old MixNumbers node to old nodes
- update documentation