On some systems having both %.o: %.c and %.o: %.cc rules confused the
make system. This is directory only has C++ code so remove the %o: %.c
rule. Also the C++ compiler should be used to link C++ object code.
The main .pcb file contains elements, and basic PCB status.
Write out a .pcb file with stub Elements for each of the devices
in the design.
Rearrange the way the files are reported to the code generator
so that we can sensibly express where the output files are.