fixed: incorrect sub path calculation for libs and doc filenames (full filenames where always converted to relative paths,
even when they are not in standard libraries paths)

Small change in print function: print footprint after zones (like in BOARD::Draw) to make pads holes visible on copper zones

pcbnew: remove old of two To_User_Unit(), redraw ratsnest on/off, magnetic cursor to start move/drag module

pcbnew: Starting work on undo/redo in pcbnew. Only some delete item commands are stored in undo/redo stack

pcbnew: Starting work on undo/redo in pcbnew. Only some delete item commands are stored in undo/redo stack

Rework on undo/redo and block functions: more efficient code to undo/redo block move and mirror operations

Rework on undo/redo and block functions: more efficient code to undo/redo block move and mirror operations

Rework on undo/redo and block functions: more efficient code to undo/redo block move and mirror operations