[kernel] Deprecates Db.Main

src/plugins/nonterm/nonterm_run.ml

src/plugins/obfuscator/obfuscator_register.ml

src/plugins/occurrence/register.ml

src/plugins/pdg/register.ml

src/plugins/postdominators/postdominators.ml

src/plugins/reduc/register.ml

src/plugins/report/classify.ml

src/plugins/report/csv.ml

src/plugins/report/register.ml

src/plugins/report/tests/report/multi_emitters.ml

src/plugins/report/tests/report/no_hyp.ml

src/plugins/report/tests/report/one_hyp.ml

src/plugins/report/tests/report/projectified_status.ml

src/plugins/report/tests/report/several_hyps.ml

src/plugins/rte/register.ml

src/plugins/server/server_batch.ml

src/plugins/server/server_doc.ml

src/plugins/server/server_socket.ml

src/plugins/server/server_zmq.ok.ml

src/plugins/slicing/register.ml