Problem: Cannot use the mouse to resize window while the focus is in a
terminal window.
Solution: Recognize nice mouse events in the terminal window. A few more
fixes for the terminal window.
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.
