support for Revise.includet, unconditionally saving buffers

• C-c C-t will include buffer with Revise.includet (@wraith1995)

• setting julia-repl-save-buffer-on-send to t will save always save buffers without asking before include and includet (@antoine-levitt)

• explain how to get more colors with eterm-256color in the readme (@antoine-levitt)

• various minor fixes