Process last capture even on timeout. Prevents last bit getting lost.
On timeout, don't allow next edge to resync decoder.
Timeout on 6 bit periods instead of 5.
Set systick interrupt to low priority.
'mon traceswo' reports serial number and interface/endpoint no for libusb.
Interrupt priorities set so TIM3 for trace is highest priority.
Increased trace endpoint packet size to 64.
Buffer many trace packets into a single usb packet. Stall on overflow.
Fixed stop bit detection in TIM3 interrupt handler.
Gareth McMullin