Pull request for V2

This is a pull request to document changes of micronucleus leading to V2. V2 is supposed to introduce major changes to the protocol. Please absolutely do not merge this right now. Danger looms!

A significant may be the introduction of polled USB, which is currently researched by gblargg/shay green in his own implementation at  https://github.com/gblargg/micronucleus

### Current ideas for V2.x ###

Changes to client firmware:
	- New device support (84,841,167,861)
	- External oscillator option
	- polled USB
	- enter bootloader by external reset
	
Changes to protocol/command line tool
	- Send different delay times for erase and program to support 481
	- Transmit data in value and index field, don't use data payload to reduce code size and improve v-usb stability
	- Move writing of tiny vector table to host tool. Reset vector patching stays on client
			-> no risk of bricking device, since bootloader will remain active
	- erase command
	- CRC check