cli (call): `tui` output implementation: - Moved original UI to a separated class, and use if with the `simple` output - By default, best output is automatically selected. For now `gui` is selected if possible, and `simple` is used as fallback. - The new `tui` output can be used to have the videos directly embedded in the terminal, either with real videos for compatible terminal emulators, or with Unicode blocks. - Text contrôls are used for both `simple` and `tui` outputs - several options can be used with `--oo` (will be documented in next commit). rel 428

You'll find install instructions in documentation (see doc/installation.rst).

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