Merge wxUIActionSimulator fixes from SOC2010_GUI_TEST branch.

Merge wxUIActionSimulator fixes from SOC2010_GUI_TEST branch.

Correct a lot of problems with the initial implementation, notably make the
API consistent across all platforms, e.g. all keyboard-related methods now
take just a wxKeyCode.

Add some useful higher-level helpers such as Text() and MouseDragDrop().

Improve documentation.

wxUIActionSimulator now works under MSW, GTK and OS X and is enabled by
default.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@65385 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775