README: update. show state of device implementations.
datetime: use the twl4030 rtc for an almost complete datetime device.
controller: mostly complete implementation. works mostly as expected.
controller: use volume keys as a and b buttons.
controller: only trigger the controller vector if the button state has changed.
i2c: set master and transmit bits in i2c_initiate_transfer.
main: fix disabling the twl4030 watchdog timer.
initial workings of i2c. just polling for now.