Separate fcserver source from its dependencies

server/Makefile

server/src/enttecdmxdevice.cpp

server/src/enttecdmxdevice.h

server/src/fcdevice.cpp

server/src/fcdevice.h

server/src/fcserver.cpp

server/src/fcserver.h

server/src/libusbev.cpp

server/src/libusbev.h

server/src/main.cpp

server/src/opcsink.cpp

server/src/opcsink.h

server/src/usbdevice.cpp

server/src/usbdevice.h

server/src/util.h