Atmel SAMD20 support
Added notes about the datasheet and NVMCTRL Security Bit
Optimised flash write, programming speed is now approx. 2x faster
Fixed SAM D20 support with reset attached.

monitor connect_srst enable can be used to connect to targets that re-use the SWCLK pin
Use external access DSU range
SAM D20 MBIST shouldn't fail silently
Ooops - Semicolon from last commit :-)
SAMD20 prints die revision