setting temperature to .5 degrees doesn't work

[RobertJansen1]

Currently, setting the temperature to 19.5 just sends a 19 degrees value to the airco unit as the units don't support half degree target temperatures.

in the upstream project, this is worked-around by mocking the temperature reading of the internal sensor and modifying the temp. we should do the same some time. the solution in #87 allows for this to be extended and should be investigated