New simplify rule for bitshift operators

Added a rule to replace bitshifts by a constant value to a divide by the corresponding power of two.
I am checking if ui is out of bounds here, so that's why I use < and ||, but we could do it you way as well. However, I actually think we need to use (uint)t.imax() since t might be a 8 or 16 bit integer, in that case (uint)-1 would not be the correct bound.