Change how Lute loads demo data

[jzohrab]

Summary

For new users, Lute should only load language data when the user requests it.

Current issue

Lute currently loads all languages and demos in lute/db/demo into the database, and as part of the release process, those lanuages and demo stories are all loaded into the baseline database, which is also committed to the repo. This loading of all of the data creates a lot of code repo thrash, eg when a new field is added to some tables (languages, books, texts, etc).

In addition, this creates problems when the demo comes pre-loaded with Japanese, but it needs to be hidden on startup ...

A few people are creating sensible defaults for all languages and stories -- these could all be available within the Lute package and then users could install it.

Changes envisioned

• change the release process to only include English and the Tutorial
• optionally include some obvious easy things like French, Spanish
• add screen for users to list and load other available languages, and potentially stories
• handle the toggle of "demo mode" somehow ... not sure what's involved just yet.

[jzohrab]

Being handled in #534 .

[jzohrab]

Released in 3.6.1.