Fix up demo documentation device compatibility list to be as general as possible to reduce changes required as Atmel releases more devices within the same USB AVR series.

Add link to third-party signed version of the official FLIP DFU driver for 64-bit Windows OSes to the DFU bootloader readme file.

Add HTML anchor links to URLs in the documentation to ensure that they are rendered correctly in the generated documentation.

Documented FAST_STREAM_TRANSFERS compile time option.

Reduced the TCP window size for the RNDIS demos (Class and LowLevel) to make them compatible with the AT90USB64x.

Re-add signature byte defines to the DFU and CDC class bootloaders -- the SIGNATURE_x defines in the AVR device header files only exist in a newer version of avr-libc than is in the Debian repositories, causing build issues on Linux.

Added preprocessor checks and documentation to the bootloaders giving information about missing SIGNATURE_x defines due to outdated avr-libc versions.

Corrections to Keyboard demo.

Removed AVRISP_Programmer project due to code quality concerns.