Lots of changes here. Added new I2C test code, a new serialTest program,
and developed the new ISR - Interrupt Service Routine
handler - much easier than the old waitForInterrupt code!

Minor tweaks to the gpio program to recognise the environment variable
WIRINGPI_DEBUG too, and removed the printing of the errors from the
main wiringPi setup routines (and added some new ones!)
Minor changes to messages being printed from wiringPiSetup()
Changed built to work marginally better.
Change to the build script to check for the presence of the I2C development
libraries.
Bumped gpio version.
Updated the build script to better try to detect lack of i2c-dev
(hopefully!)
Also updated all the mmap code in wiringPiSetup() to make it a bit more
sane and efficient to a degree.
Merge branch 'master' of git://git.drogon.net/wiringPi

Conflicts:
	wiringPi/Makefile