Seperation ov PCSC and libnfc

I've took the liberty of seperating PCSC and libnfc.
Both backend implementations run now seperately.
You can simply use --without-pcsc to disable PCSC and
--without-libnfc to disable libnfc. Although one of the two backends
must be enabled.
Furthermore both can be enabled. I have no idea what for but be my
guest ;-)
Merge branch 'pcsc' of github.com:hackerhelmut/libfreefare-pcsc into pcsc

Conflicts:
	examples/Makefile.am