common_operation_tree.vhd

The enable vector ripples now through. This was neccesary for two situations: * two adjacent inputs are disabled. In that case the result should also be disabled in the next stage. 
* In case an odd number of inputs is used. Then the last enable bit should be carried on to the stage where the input is actually connected to a common_operation block. 
 
-- line, and those below, will be ignored--

M    common/src/vhdl/common_operation_tree.vhd