doc: grammarcheck of documentation before 3.8 release. * build-aux/mk-opts.pl: Use @qcode macro around quoted code options. * liboctave/numeric/DASPK-opts.in, liboctave/numeric/LSODE-opts.in: Use @qcode macro around quoted code options. * libinterp/corefcn/module.mk, liboctave/numeric/module.mk: Option handlers must also depend on Perl script mk-opts.pl. * libinterp/corefcn/bitfcns.cc, scripts/help/type.m, scripts/image/imfinfo.m, scripts/miscellaneous/dir.m, scripts/plot/stem.m, scripts/plot/stem3.m, scripts/plot/subplot.m, scripts/specfun/expint.m: grammarcheck of documentation before 3.8 release.