Add variable function (expression builder) direct to dimension window (dialog)

Now if we want to calculate dimensions, we have to do it in multiple steps. Make a dimension, create variable with functions or operations, create a construction point, and assigned variable to that point, and report the point.

It will be more elegant if you add a checkbox to dimension window to enable and add some functions & operators to the dimension (the expression builder). The expression builder would be integrated into separate tab on all dimensional windows.