Matrix4.leftTranslate

[abarth]

Matrix4.translate is great when you want to multiple in a translation on the right of a matrix, but sometimes you need to multiple a translation in on the left. It would be valuable if there was a version of Matrix4.translate that applied the translation on the left (e.g., leftTranslate).

/cc @johnmccutchan

[johnmccutchan]

@abarth Please confirm that this commit fixes this issue:

369422c

[abarth]

Yes, perfect. Thank you.

[johnmccutchan]

@abarth vector_math 2.0.3 on pub contains Matrix4.leftTranslate.