Require authentication for unread-counts; guests don't need this.

for every sub in a group or every group (that the user has
access to).
Avoids sending a long list of sub/group codes in the query string
for no good reason, which is a problem if you like to carry an
insane number of dead echoes or whatever.

If file type is known to ctrl/mime_types.ini,
and if files_inline is true in modopts.ini->[web],
and if it's not application/octet-stream,
set content-disposition to inline.

darkmode can be disabled in modopts.ini, and darkmode will use macos preferences if not set previously

This should be use in all the other places, but this was enough for
me to debug the issue at hand.

viable best-guess settings ({web_directory: '../webv4}). This
gives lib/init.js a chance to set further defaults.

maybe that'll do something.

component (xjs) file from webv4/mods/components/ if available,
or from webv4/components if available there, or output nothing
at all (and return false) otherwise. Semi-tested, the best kind
of tested.