Add 'tethered' and 'holding' as displable status conditions for X11.
For tty-style status, they're ordinary. For 'fancy status', tethered
is displayed in the 'trapped' slot (since they'll never both be shown
at the same time) and holding is displayed in the 'held' slot (same
situation).
It's more proof of concept for overloading of status conditions than
adding useful specific conditions. This was the third iteration; the
first two were either too fragile or used even more code. It could
probably be simplified by making some mutally exclusive conditions be
more like hunger and encumbrance instead of being distinct flags
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