* All header files used to create the PCB common library now compile as
stand alone code. This prevents the need to define them in a specific
order to make source code compile properly. It should also now be
possible to relocate the source code to build the common PCB library
to a separate folder.
* Move various locate functions into the appropriate board item object.
* Unified best zoom for all frames derived from PCB_BASE_FRAME.
* Remove track.cpp as it is no longer needed.
* Dead code removal.
* Remove scary frame window pointer member from board item objects.
* Add draw bounding box to gerber draw item for debugging purposes.
* 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.
Wayne Stambaugh
jean-pierre charras
Jerry Jacobs