MayaScene bindings now catch boost python exceptions

I ran into a case where some custom attribute readers were erroring in caribou and crashing maya. Turns out this is because they were raising a boost::python::error_already_set, which wasn't getting caught by anything, and triggered another uncaught exception. I've now put try/catch blocks in the CustomTagReader and CustomAttributeReader to avoid this situation in the future.
Avoiding use of deprecated operator[]

The headers indicate using operator() instead which make sense from the source code as we are doing read-access and there's no need to expand the array if indices are greater than the current size.
Adapting all classes used in calls to despatchTypedData to use raw pointers instead.

Took the chance to also optimize a bit on a couple of spots by calling reserve on vectors which the resulting size was known.
Merge pull request #301 from davidsminor/mayaScenePythonExceptions

MayaScene bindings now catch boost python exceptions
Merge pull request #302 from ldmoser/fixBuild9

Fix build