Problem:    Cannot define a toolbar for a window.
Solution:   Add a window-local toolbar.

Problem:    Terminal debugger jumps to non-existing file.
Solution:   Check that the file exists.  Add an option to make the Vim wide
            wide. Fix removing highlight groups.

Problem:    Terminal debugger can't evaluate expressions.
Solution:   Add :Evaluate and K.  Various other improvements.

Problem:    The terminal debugger can't set breakpoints.
Solution:   Add :Break and :Delete commands.  Also commands for stepping
            through code.

Problem:    No debugger making use of the terminal window.
Solution:   Add the term debugger plugin.  So far only displays the current
            line when stopped.