msp430 x2 usci: getStopBit() and getTransmitReceiveMode duplicate

Some how these two functions got duplicated.  (probable merge
issue from the mainline).

Fixes #22.
msp430 adc12: turn off warning about bitfield code gen

adc12, usart, and usci bitfield code effected.  Just turn the
warnings off.   Bitfields work fine.  Been using the bitfield
code generation in 4.6.3 for some time now.  Used in active
code for ADC12, the USART in the 1611 code, and the USCI code
for the 2618 code.
msp430 x1 dma: update mods for new unified dma driver
msp430 dma: transferDone has no parameter.
4bitle: return type of Send.cancel should be error_t

was uint8_t but should have been error_t to match the
interface of AMSend.cancel.
msp430: add __TOS_MSP430_CORE__ define to denote what API release it is.
Add info about different main repositories
Add note about getting tinyos-release
cc2520: remove various bits of cruft