Fixed initialisation bug and compilation error in gatereg module. Added mips_pipelined to test suite. Fixed several bugs in assignment3 MIPS module

tests/tests.sv

@@ -4,4 +4,5 @@
 `include "tests/instruction_classifier_tb.sv"
 `include "tests/shifter_tb.sv"
 `include "tests/alu_tb.sv"
-`include "tests/mips_singlecycle.sv"
+`include "tests/mips_singlecycle.sv"
+`include "tests/mips_pipelined.sv"