Blinken Button SPI ~~~~~~~~~~~~~~~~~~ Adds SPI support to the Blinken Button by Interactive Matter[1]. This allows the 8x8 LED display to be controlled by another MCU. The Blinken Button receives frames from an SPI master, which are shown on the display. A frame consists of 8 bytes, each of which represents rows 0 to 7. [1] http://interactive-matter.org/how-to/blinken-button-for-beginners/