Add support for the ATtiny88

Add pins_arduino.h. Implementation is experimental. Compiles with standard Arduino core and TinyNoMillis.
Add support for the ATtiny88

Add support for the ATtny88, using the ArduinoISP as an uploader. Configure for 1MHz internal clock. Using the TinyNoMillis core.
Specify upload protocol

Specify ArduinoISP as upload protocol.
Add 8MHz clock option

Support for internal 8MHz clock.
Update extended fuses

Disable self programming.
Merge pull request #24 from tomscatliff/master

Initial support of ATTiny88