[stm32l] Remove as much device specifics as possible

And tidy up commentary
[stm32f1] New platform for STM32VL Discovery board

Functionally identical to the STM32L Discovery board platform.  Only
differences are the _arch_ functions dealing with GPIO and clock config.
libopencm3 makes it easy for these to be mostly common code.

(Old newlib syscalls still in place for now)
Remove support for deprecated types we don't need
[openocd] Support multiple OpenOCD interfaces simultaneously

I wanted/needed to support multiple OpenOCD windows open at the same
time, so added a local openocd.cfg for each platform.  Starting openocd
in that directory will "do the right thing"

Tested with OpenOCD 0.7
Generated headers should not be committed
Update contiki upstream
Update to latest libopencm3
[boards] Add avr-arm jtag helper

Designed for the milling machine at work, to help program the avr raven
usb stick, hopefully from any arm jtag board