the reserved bootloader size is set in the NVM user configuration
and allows to know the application start address (e.g. after the
bootloader)
Change-Id: I9dda27d6401caabb4a6470aa3fe9691f63097136
the USB control request are now handled in separate function
depending on the direction (IN or OUT).
download and manifestation are handled.
numerous additional state machine fixes are included.
Change-Id: I5237393c2789fdeddca2182da25ef417a2e71216
uses the USB CDC ACM example code as template to create a USB DFU
description according to USB DFU specification version 1.1
USB DFU stack is under LGPLv2.1 or later license
Change-Id: I7bd6cb46b734ffe8a51f2de7083b4f9e76d385e6