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
Fixes M4 compatibility

Switched all instances of Future.immedate to Future.value
Merge pull request #86 from toji/futures-fix

Fix M4 compatibility
Adding AssetPackTrace.
Merge pull request #87 from donny-dont/features/asset_pack_update

Adding AssetPackTrace.
Merge branch 'master' of https://github.com/johnmccutchan/spectre
Fix Copyright to something that has legal meaning.