Changes for SIC-receiver:

1. in dlsim.c: now we check for the receiver type and, if SIC,  proceed through encoding, modulation, LLR compuattion and decoding
of the decoded TB0.
2. Implementing routines for vector-vector multiplication and vector-vector subtraction
3. Adding some printouts for debuging purposes.
4. New functions: modulation_SIC, dlsch_qpsk_llr_SIC
5. In phy_scope.c: changing llr plotting: now for the length of coded_bits_per_cw.