Add Int32Array and Uint32Array support to ComponentDatatype

Fixes #1647
Fix typo in comment.
Specs for ComponentDatatype
Merge remote-tracking branch 'origin/master' into issue1647
Changes after review.
Merge branch 'master' into issue1647
Properly compute numberOfVertices when unpacking geometry indices.
Merge remote-tracking branch 'origin/master' into issue1647
Merge pull request #1650 from AnalyticalGraphicsInc/issue1647

Properly pack geometry indices for vertices greater than 64k