Introduce the concept of a DRC_PROVIDER which allows
to separate the various DRC functions to their own
areas. This allows, amongst other things, a slimmer core
DRC class, and allows DRC functions to be separately testable.
The courtyard DRCs (overlap, missing and malformed)
are the first victims, so instrumentation can be added to this function.
Add some unit tests on this DRC function, as well a few re-usable PCB-based
utility functions in a library (qa_pcbnew_utils) that could be shared between
unit tests and other utilities.
Also modify the linkage of kiface objects, as this is not
supported by older CMake versions.
This was accidentally removed with the reversion of the application
of the wrong patch (8f11a2133).
QA: fix object files
Devolve the logic as to whether a pad should be numbered or not
to a pad utility function. Add a very simplistic test for this
function (demonstrating how to test BOARD_ITEMs in general).
Fixes: lp:1804787
* https://bugs.launchpad.net/kicad/+bug/1804787
John Beard