Added twi.c which simplifies working with TWI(i2c)
Added twi.c which simplifies working with TWI(i2c)

The rtc now works and we can query it for a new timestamp
Removed debugging printf statements
Made the current flag read and writes more clear
Removed uncommented print statements
Merge branch 'twi_support' of github.com:UnicornRaceEngineering/g5-nodes into twi_support

Conflicts:
	examples/twi_master/m41t81s_rtc.c
	examples/twi_master/m41t81s_rtc.h
	examples/twi_master/main.c
	libat90/twi.c
	libat90/twi.h
Made logic flow simpler / more explicit
Added Mask defenitions for all values on the rtc
The rtc now works again.

This is a hack
We can now set the RTC time and set default flags

We still need to handle HT and BT flags
Added comments and fixed typos
Fixed issue causing wrong time to be sat

also collaped two macros into one function. As a hack on the i have
inserted a fixed delay after each twi stop condition wich is needed to
make the rtc behave
Better formatting of flag macros in the rtc driver
Fixed doxygen comments
Moved twi_init into the m41t81s init function

It made no sense that we had to call this our selves.
Also removed unused defines used for debugging
Moved all drivers into their own module

This gives better sepperation of modules so more nodes can share driver
among each other
Merge branch 'driver_seperation'