Never refresh controls from EVT_PAINT handler in wxPropertyGrid.

Never refresh controls from EVT_PAINT handler in wxPropertyGrid.

Refreshing the controls after finishing repainting the grid results in an
infinite stream of paint events, so don't do this, especially as this doesn't
seem to have any bad consequences under wxGTK which was the only major
platform where this behaviour was enabled.

Also rename wxPG_REFRESH_CONTROLS_AFTER_REPAINT to just wxPG_REFRESH_CONTROLS
and keep the control refreshing code for wxGTK only in a couple of places
outside of EVT_PAINT handler to be on the safe side.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@70509 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775