usbptp filesystem for plan 9

doesnt implement flush
no caching of downloaded objects
may only work with my nikon coolpix p50

usbptp.c.old is the version for the old plan9 usb stack just for
reference.

tell me if your camera works or fails so we can make a list
of supported devices or i can help you debugging :)

you can contact me at:

cinap_lenrek AT gmx DOT de