General purpose scalar math node

A collection of scalar->scalar y=f(x) math nodes.
Provides 23 scalar functions from Python Math library, select which one
via dropdown, the node label updates with the selected function which
gives good usability when nodes are collapased.
Aligned version

Version matches version in __init__.py , should use that info here also.
Merge pull request #10 from ly29/master

Fixed wrong version shown in tools and general math node