Allow basic Arithmetic in Variable and Conditions

We often have several values that are related. For example the number of ADC Channels is twice the number of ADC instances. Now we need two variables. It would be easier if we could say: Use this variable value, but times 2.

Same for conditions. We could have one set of ADC related condition names and values instead of two. For example: ishcondition="ADC_CHANNELS"/2

We would like to see support for addition, subtraction, multiplication and division.