fix annoying compiler warning "'usbFunctionDescriptor' used but never defined"

Because in order to save a few bytes of code, the usbdrv.c is included in main.c,
instead of being linked.
This feature is supported by the usb driver, but needs "USB_PUBLIC" to be defined
as static.
Even when it is not really used in the code,
"static usbMsgLen_t usbFunctionDescriptor(struct usbRequest *rq)" isn't optimized
out at this level of compilation.
Since it is never defined, the warning pops up.

Fix: Define a dummy function which becomes optimized out later.

Signed-off-by: Stephan Baerwolf <stephan.baerwolf@tu-ilmenau.de>
fix warning "optimization may eliminate reads and/or writes to register variables"

Signed-off-by: Stephan Baerwolf <stephan.baerwolf@tu-ilmenau.de>
fix warning "integer overflow in expression" in updater

Signed-off-by: Stephan Baerwolf <stephan.baerwolf@tu-ilmenau.de>
fix automated feature selection due to bugfixes to still fit into bootloader

Signed-off-by: Stephan Baerwolf <stephan.baerwolf@tu-ilmenau.de>
migrate to new v-usb driver release 20131128

The mainline master-HEAD commit 6f64e80f219273967d6ac7096f3ca3d7db5a0e79
was used.

https://github.com/obdev/v-usb/commit/6f64e80f219273967d6ac7096f3ca3d7db5a0e79

Signed-off-by: Stephan Baerwolf <stephan.baerwolf@tu-ilmenau.de>
USBaspLoader v0.97.1 stable release

  -  fixed bug causing the watchdog timer to continously reboot
  -  new feature for watchdog enabled bootloader (and updater)
  -  cleanup compiler build warnings
  -  new and improved v-usb driver

Because users ofter were confused by the provided hexfiles and
The firmware from tinyUSBboard, precompiled hexfiles are not
further supported.
Please use binaries provided for tinyUSBboard instead:

	http://matrixstorm.com/avr/tinyusbboard/

Signed-off-by: Stephan Baerwolf <stephan.baerwolf@tu-ilmenau.de>