PR Summary

This is a first implementation of the main ToolManager Tools for the wx backends:
SaveFigure, SetCursor and Rubberband
There's no ToolbarWx implementation. The tools are for embedding a FigureCanvasWxAgg and to be triggered by the program.

This is a replacement for PR #10145.

It was tested under Windows/Python 3.6/Phoenix and Mac OS/Python 2.7/wxPython 3.0.2.

The implementation of Rubberband under Mac OS is not optimal, but overlays and DC.SetLogicalFunction do not work on Mac OS on any wxPython version.
Re-using the Mac OS rubberband code from the NavigationToolbar2Wx would have created quite unreadable code as RubberbandBase is using screen coordinates. The code could probably be optimized with a changed implementation of FigureCanvasWxAgg.

The other tools are mainly copy & paste from NavigationToolbar2Wx and the Qt/GTK3/Tk implementations of the tools.

My motivation for the current pull requests is to ship a fully working example with wxGlade that demonstrates how to build a GUI with a matplotlib canvas and use most of the control features that people would need. I could strip down this example if required. The full example is probably too large for distribution with matplotlib and also it's not finished yet.

PR Checklist

• Has Pytest style unit tests
• Code is PEP 8 compliant
• New features are documented, with examples if plot related
• Documentation is sphinx and numpydoc compliant
• Added an entry to doc/users/next_whats_new/ if major new feature (follow instructions in README.rst there)
• Documented in doc/api/api_changes.rst if API changed in a backward-incompatible way