Added C-code generator + test to TDDD55-lab

lab3-4/Makefile

lab3-4/codegen-test.sh

lab3-4/codegen.cc

lab3-4/codegen.hh

lab3-4/main.cc

lab3-4/stl.h

lab3-4/symtab.cc

lab3-4/symtab.hh

lab3-4/test/README.md

lab3-4/test/expression_output_ref

lab3-4/test/expression_test.prog

lab3-4/test/factorial_output_ref

lab3-4/test/factorial_test.prog

lab3-4/test/fibonacci_output_ref

lab3-4/test/fibonacci_test.prog

lab3-4/test/simple_array_output_ref

lab3-4/test/simple_array_test.prog

lab3-4/test/simple_array_test_output_ref

lab3-4/test/simple_simple_array.prog

lab3-4/test/sort_test.prog