Software SPI class modification for Arduino and MCP49xx DACs.
Original SoftSPI repository: https://github.com/MajenkoLibraries/SoftSPI
Original DAC_MCP49xx repository: https://github.com/exscape/electronics/tree/master/Arduino/Libraries/DAC_MCP49xx
DAC_MCP49xx repository that uses this Software SPI implementation: https://github.com/bartoszxkozlowski/DAC_MCP49xx