Fix #1749 by adding an OIT flag.
CHANGES.md
Make OIT a constructor option, to save resources.
Merge remote-tracking branch 'origin/master' into oit-flag
Add unit tests.
Switch to use defaultValue.
Add read-only flag, and update tests to use new flag.
Merge pull request #2120 from AnalyticalGraphicsInc/oit-flag

Fix #1749 by adding an OIT flag.