Problem:    Cannot specify mappings for the terminal window.
Solution:   Add the :tmap command and associated code.  (Jacob Askeland,
            closes #2073)

Problem:    No terminal emulator support.  Cannot properly run commands in the
            GUI.  Cannot run a job interactively with an ssh connection.
Solution:   Very early implementation of the :terminal command.  Includes
            libvterm converted to ANSI C.  Many parts still missing.

Problem:    Building the command table requires Perl.
Solution:   Use a Vim script solution. (Dominique Pelle, closes #1641)