Magnetic field sensors

• first generation tests with hmc5883l and qmc5883l.

First release, example project supported.

• Fixes for power sensor bl0397, example for Gosund SP1 switch in examples project works now.
• All examples in project muwerk/examples are now supported.

Test-release 2, documentation ongoing

• Multiple new sensors
• All display code (GfxPanel) moved to project mupplet-display
  Note: documentation is still incomplete and ongoing.

Test-release

DHT BMP180 and Oled-sensor for testing.