User mode handling needs work

[cooper]

Any place where we force a user mode change, we have to literally lookup the letter and use ->do_mode_string(). This is horrendous. We need ->do_modes() or the like. We probably can't use the modes package since it checks cmode types and parameters and whatnot.

Hmm, since user modes do not have parameters, we could just use array refs of only mode names.

Also, oh my lord:

    # it's easier to do this than it is to
    # keep track of them
    # FIXME: PLEASE!
    $str =~ s/\+\+/\+/g;
    $str =~ s/\-\-/\-/g;
    $str =~ s/\+\-/\-/g;
    $str =~ s/\-\+/\+/g;