v0.8.0

• new devices
  • mcp3008: add implementation for MCP3008 ADC with SPI interface
  • semihosting: initial implementation of ARM semihosting
• enhancements
  • espat: refactor response processing for greater speed and efficiency
  • espat: implement mqtt subscribe functionality via blocking select/channels (experimental)
• bugfixes
  • st7789: fix index out of bounds error
• examples
  • Add espat driver example for mqtt subscribe