60: getpos() doesn't report the offending keystroke accurately when
rejecting M-something as a movement keystroke while moving the cursor;
61: typing M-N as a command keystroke produces
|Unknown command 'M-
| '.
where the '.' on the second line clobbers the top line of the map.
I can't reproduce the first one without extending the altmeta hack
[a run-time option to treat two char sequence ESC c as M-c] to getpos()
and nh_poskey(), which I've done for testing but am not including here.
I can't reproduce the second as it's described, but M-^J produces
|Unknown command 'M-
|'.--More--
and this fixes that, with a general fix that applies to any meta char.
The diffs include some cleanup/groundwork for maybe extending altmeta.
3ec592e3f1