#14 bw-cumulative patch for patches 11-13 based on 2.1.5

[Bernd Wagner]

This patch merges patches 11, 12, 13 to provide a basis for subsequent patches in order to avoid merging problems.

There is a graphical circuit diagram README_i2c-23017_circuit_diagram.jpeg (sourceforge.net) which should be added as additional README file for patch 11.