Fixed unwanted conversions in single shot mode / Changed Auto_Range.ino

For all settings in the conversion register the conversion register is read, the relevant bits are set to zero and then the relevant bits are set to the desired values. What I had overlooked is bit 15. When reading, a 1 means that no conversion is ongoing. When writing a 1 means in single shot mode that a conversion is triggered. Therefore all settings triggered a conversion in single shot mode.

Moreover I have simplified the Auto_Range.ino sketch. I was a bit more complicated than necessary.