Blender Git Loki

Extra flags/attributes for OpNodes - Timing stats + Flags

* Added attributes for logging how long it took to evaluate an operation
(and/or the last timestamp when it was evaluated)
* Added flag to tag operations which require the use of Python
(there are implications for the scheduler here re-GIL threading lock issues
but also our more general Py-Security concerns). See r58801 for example
of threading issues...