* Change default build to enable wxDC zooming.
* Move sheet label find function into SCH_SCREEN object.
* Move draw screen items function into SCH_SCREEN object.
* Remove redundant page print method from SCH_EDIT_FRAME.
* Add method to hit test for all items in SCH_SCREEN.
* Add method for testing if junction is required in SCH_SCREEN.
* Fix Doxygen waring in help_common_strings.h