Add a scaled vector API naming poll

[LeXXik]

A poll for public API name in #5702.

[kungfooman]

Maybe just my old C engine sentimentalism:

https://github.com/ioquake/ioq3/blob/b1e6ef14254fdcb77cbe2f602c22549d3fb0eb78/code/qcommon/q_math.c#L826-L830

mulAdd - first we multiply the vector, then adding result to this