The actual terminfo entries we ended up with for cursor changes are Cs,
Ce, Ss and Se (not Cc, Ce, Cs, Csr). So use and document these instead
of the ones we were using earlier.
escape "Ss", becuase groff thinks it has found a macro;
revert r1.156 "Add support for focus notifications when tmux pane changes"
beck@ found annoying beeps if a machine was shutdown while tmux is running
and you then focus in/out of an xterm; kettenis tracked it down to 1.156.
Merge branch 'obsd-master'