* 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.
* Replace use of wxICON by new icons declaration.
* Remove unused files.
* Fix filenames inconsistencies between old and new icons.
* dialog_erc handle variable size icons in erc matrix.