several renamings, dropped some dead code

src/snc/gen_ss_code.c

src/snc/gen_ss_code.h

src/snc/gen_tables.c

src/snc/gen_tables.h

src/snc/parse.c

src/snc/parse.h

src/snc/phase2.c

src/snc/phase2.h

src/snc/snl.lem