Add -P to move-pane to move a floating pane to a specific place
(top-left, bottom-right). Get rid of the not-so-useful default { and }
swap-pane bindings and use the keys instead for moving to top-left,
top-right and add M-{ and M-} for bottom-left, bottom-right.
Extend client mode so the preview can be changed to a view with a
summary of the client terminal and its features, intended to make
troubleshooting easier. "choose-client -i" or the "i" key in the mode.
sys/vfs: wake vclean after failed vnode lock attempts
vclean() sets VXLOCK and waits for v_lockcount to drain before taking
the vnode lock with LK_DRAIN. vn_lock() already woke that waiter when a
racing VOP_LOCK() succeeded, noticed VXLOCK, and had to drop the lock
again.
Do the same wakeup when the racing VOP_LOCK() fails. A failed attempt
still decrements v_lockcount, and if it was the last in flight attempt,
vclean() must be notified that the drain condition is satisfied.