Added TWI baud rate prescaler and bit length parameters to the TWI_Init() function (thanks to Thomas Herlinghaus).

Add new ARCH option to the makefiles to (eventually) specify the target device architecture. Update non-usb peripheral drivers to reflect future multiple architecture support.

Add static keyword to all project globals whose scope should be restricted to the same module as they are declared in.

Tighten up the HID class bootloader code slightly, document that it currently exceeds 2KB of bootloader space for all models other than the Series 2 USB AVRs.

Add const to all project descriptor definitions for safety.

Documentation improvements - put driver example code into its own section, fix incorrect and missing section names.

Make a new general RingBuffer.h misc library driver, instead of the per-application LightweightRingBuff.h ring buffers. Change over projects to use the new driver.

Add ORDERED_EP_CONFIG to the device Projects (only) that use only a single class driver, or where the endpoint ordering is fixed, to save on compiled binary size.

Added new GCC_FORCE_POINTER_ACCESS() macro to correct GCC's mishandling of struct pointers.

Add DEVICE_STATE_AS_GPIOR=0 compile time option to the library projects, to reduce compiled binary size.