use tutor code from rascal project, drop dependency on rascal-tutor prokect and inject screenshotter into the tutor repl command executor

[jurgenvinju]

This uses the original tutor code that has been moved to the rascal project (snapshot dependency on the adopt-tutor branch).

• no more dependency on the rascal-tutor project
• injects a screenshot feature into the tutor of the rascal project
• adds compile-time dependencies on selenium and run-time dependencies on Chrome and chrome-test-driver to the current project

[jurgenvinju]

tested on several projects (flybytes, drambiguity) this seems to work without any impact.