Problem: Mimicked block mode for cmdline entered while expanded
does not work intuitively for repeated commands yielding
messages exceeding the screen height. The expanded cmdline
resizes and scrolls to bottom/top when appending a message
and entering the cmdline. Also includes the entered command,
as opposed to the UI1 behavior.
Crash when scrolling to bottom of pager due to recursive
uv_run after shell message callback executes `nvim_command()`
with 'showcmd'.
Solution: Still mimic block mode when entering the expanded cmdline,
but when the entered command emits a message open the pager
with the current message content in the expanded cmdline.
Always route typed commands to the pager when it is open.
Use `nvim_buf_set_cursor()` instead of `nvim_command()`.
52dd62aa6e