Move invariant related tests into a new file and add more cases.
Fix year in disclaimer.
Add texStorage2D test
Add more cases
Merge pull request #734 from zhenyao/invariant

Invariant
Merge pull request #735 from bjacob/texstorage2d

Add texStorage2D test
add WebGL2 conformance test for new texture formats, and sized internalformats
Merge pull request #736 from bjacob/tex-new-formats

WebGL2 test for new formats and sized internalformats