Initial commit for WS2812 support

Hi Ihsan,

I played a bit around with little-wire v1.2 and found it pretty nice. I added support for WS2812 based RGB LEDs and LED-Strings. These are programmable and chain-able LEDs with integrated PWM that can be controlled from a single pin. These devices and strings based on them are quite popular right now. I hope you find this useful.

I added two functions: 
- ws2812_preload: loads rgb value to an internal buffer in the tiny85
- ws2812_write: writes buffer + current rgb value to the led string.

I limited the internal buffer to 64 leds. In principle this could be increased by using more SRAM. 

Let me know if you want to include this and if you want anything changed.

Regards,
Tim (cpldcpu)