* Move undo item copy global variable into schematic editor frame object
member variable.
* Add helper methods for accessing the undo item copy member variable.
* Fix undetected bug when changing a text type.
* Added an exchange command to the undo/redo base class for handling undoing
a changed item type which cannot be undone by swapping out the variables.
* Revert change to common/hotkeys_basic.cpp that broke hot key behavior.
* Lots of coding policy changes while making the changes above.
* Move locate function code into schematic screen object.
* Move test for junction needed into schematic screen object.
* Move test for marking connected items into schematic screen object.
* Move delete item function code into schematic screen object.
* Move delete all markers code into schematic screen object.
* Add method for locating multiple items in schematic screen object.
* Fix minor bug in schematic field object hit test declaration.
* Initial encapsulation work on item picker object.
* Remove duplicate doxygen comments from item picker object source file.