fix a compil warning.
CvPcb: fix regressions :
Shows now a void field instead of the dummy footprint name $nonane (whenthere is no footprint selected in netlist).
The active footprint selection changes only if a new component is selected from the component file,
and does not change just when the next component is automatically selected, after a footprint selection.
Speed up delete association and auto associe.
* 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.
* Split out application specific command IDs to prevent unnecessary rebuilding.
* Eliminate duplicate menu and tool bar command IDs.
* Split component library editor and viewer definitions to separate header files.
* More component library and document file merge code.
* A bunch of minor string readability and consistency fixes.