Include a pre-built database for ete3.

[AlphaSquad]

And finally, it would be great to include a pre-built database for ete3.
Currently, it is generated during the first execution.

Thanks again,
Florian

Originally posted by @fplaza in #125 (comment)

[AlphaSquad]

Optimally there would be a prompt whether to build a new database or use an existing pre-built one. Providing databases which become outdated pretty quick comes with its own set of problems.