Detect text encoding with juniversalchardet.

- When opening files in the built in editor for display, detect the
  encoding with juniversalchardet, so that the correct encoding will be
  used.
- Only supported in the JavaConsole (non-privileged).

Change-Id: If35229c4aee97526eab10be59a40d1dac3e43036
(cherry picked from commit b0d83a69)