* Delete Single Pad Net option does not delete the net if a zone use this net (i.e. is attached to this pad).
* pcb_parser accept now negative netcodes in zones (can happen with old files, which previously could crash Pcbnew)
* pcb_parser accept now files with incorrect or missing net count (can happen with old files, which previously could crash Pcbnew)
* if a zone has a non-existent net name it now keep this net name, and DRC detect it (previously, the net name was lost, and the DRC did not tected this issue).
* Drc test: now detect a "dead" net, i.e. a net with 0 pads, but still used by a zone. It happens easily after a schematic modification, when a net disappears or is renamed.
Pcbnew: better test for allowed layers when creating/editing Dimensions and some other Graphic items
Drc: fix comments and messages for some drc tests.
To do: fix issues in active layer selection when creating a track and layer pair selection dialog
This is *a work in progress*, so some features are missing, and/or could be modified.
Mainly keepout zones are not yet exported to autorouters, and pads are not taken in account.
Some code cleanup in polygon.*
* Correct all user strings and comments for the correct capitalization of
application names according to JP. They are KiCad, Pcbnew, CvPcb,
Eeschema, and GerbView.
* Add a note the the user interface policy about the correct capitalization.
* 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.