Insert comparator component into ALU block (ALU structure extended), update CU

ALU output of the CU now has 1+3 new bits (for a total of 9):
-the 3 new bits (8 downto 6) are used to configure the comparator block (can't use bits 2 downto 0, because it needs to be configured at the same time as the arithmetic block);
-the function of bit 4 (mustchangetolh) has been moved to bit 5;
-the selection bits for the big mux inside the ALU have been moved from "3 downto 2" to "4 downto 3"
-bits 2,1,0 are still used to configure the active block inside the ALU (arithmetic, logic, etc.); they have been routed to the comparator's config input as well.

everything in CU_HW.vhd has been updated accordingly.