Also, with -a, dump a series of screens making up the ANSI, rather than the
last screen.

This allows optimizing tall ANSIs.

Update scrollback to use vmem_gettext()
Update all the things I previously updated for the new cterm_init() prototype

So now I expect things to work again... though X11 mode may have issues,
and SDL overlay mode is dog slow.

Update everything to use that instead of 0x00 and 0xff.  Should only impact
the use of the close window control in Windows, X, and macOS.

lines, fix cterm_init call.

Outputs both an animated version and a static version.

(or stdin if no file specified)