At least in neovim, `│vi:` is not recognized as a modeline because it
has no preceding whitespace. After fixing this, opening a file yields
an error because `net` is not an option. (`noet`, however, is.)
This change fixes minor bugs and adds a feature, which lets us store the
ELF symbol table, inside the ZIP directory. We use the path /zip/.symtab
which can be safely removed using a zip editing tool, to make the binary
smaller after compilation. This supplements the existing method of using
a separate .com.dbg file, which is still supported. The intent is people
don't always know that it's a good idea to download the debug file. It's
not great having someone's first experience be a crash report, that only
has numbers rather than symbols. This will help fix that!
