Updates to the build process

Moved the extensions into wiringPi from gpio and made it more general purpose
more so that RTB and anything else can dymanically add devices
into wiringPi.
Changes to GPIO to updates for the SPI and I2C module loads
Added gpio unload for SPI and I2C.

Added a new way to setup SPI - by passing the mode in.

Support for the new Pi2 thing too

gpio/Makefile

@@ -4,7 +4,7 @@
 #	  A swiss-army knige of GPIO shenanigans.
 #	https://projects.drogon.net/wiring-pi
 #
-#	Copyright (c) 2012-2013 Gordon Henderson
+#	Copyright (c) 2012-2015 Gordon Henderson
 #################################################################################
 # This file is part of wiringPi:
 #	Wiring Compatable library for the Raspberry Pi
@@ -38,7 +38,7 @@ LIBS    = -lwiringPi -lwiringPiDev -lpthread -lm
 # May not need to  alter anything below this line
 ###############################################################################
 
-SRC	=	gpio.c extensions.c readall.c pins.c
+SRC	=	gpio.c readall.c pins.c
 
 OBJ	=	$(SRC:.c=.o)
 
@@ -82,6 +82,3 @@ depend:
 	makedepend -Y $(SRC)
 
 # DO NOT DELETE
-
-gpio.o: extensions.h
-extensions.o: extensions.h