added database funcationality and primary user reference code

README.md

examples/pu_rx_1_channel.grc

examples/pu_rx_4_channel.grc

examples/pu_tx_1_channel.grc

examples/pu_tx_4_channel.grc

examples/run_dsa_database.py

examples/test_dsa_database.grc

grc/CMakeLists.txt

grc/cdc_dsa_db_connect.block.yml

grc/cdc_fixed_pdu_generator.block.yml

include/cdc/CMakeLists.txt

include/cdc/dsa.h

include/cdc/dsa_database.h

include/cdc/dsa_db_connect.h

include/cdc/dsa_db_interface.h

include/cdc/dsa_pu_scenario.h

lib/dsa_database.cc

lib/dsa_db_connect_impl.cc

lib/dsa_db_connect_impl.h

lib/dsa_db_interface.cc