Use new vector_math.

Signed-off-by: John McCutchan <john@johnmccutchan.com>
Merge branch 'master' of https://github.com/johnmccutchan/spectre

Signed-off-by: John McCutchan <john@johnmccutchan.com>

Conflicts:
	pubspec.yaml
Use new vector_math repo
Merge branch 'master' of https://github.com/johnmccutchan/spectre
Fix Copyright to something that has legal meaning.