Add bd command to delete a buffer.

The history can be accessed using the arrow keys.

Completely rewrote the io/graphics.rs redraw function.

Completely prevents the cursor from walking offscreen.
Also fixes several crashes when pressing 'z'. I still don't
understand how those are supposed to work anyway, but allowing
the cursor to go offscreen is never a good idea.

Allows for chained short options (e.g. -Clx)

Add support for --version, --help/-h and -R.
-R is without function as of now.

Fixes #29

Better documentation, hints on edit and not on cursor movements, missing hint detection in debug mode