This commit adds beta support for running a shell or other program
within a micro view.
Use the `> term` command. With no arguments, `term` will open your
shell in interactive mode. You can also run an arbitrary command
with `> term cmd` and the command with be executed and output
shown. One issue at the moment is the terminal window will close
immediately after the process dies.
No mouse events are sent to programs running within micro.
Ref #243
The option is `scrollbar` and is off by default. The scroll bar is
not interactive (you can't click and drag it) but this will likely
be fixed in the future.
Ref #869