plat: stm32: remove unused function
misc: cleanup out dated TODOs
plat: stm32: remove trivial script code
doc: typo update
plat: stm32: merge updates from libmaple.

Commits merged (in timeline, latest first):

commit 13635d539f6f221110705de3b17bd3267cbc68e0
Author: Marti Bolivar <mbolivar@leaflabs.com>

    usb_cdcacm: Reset transmitting flag in usbReset().