Add triggers while enabling FTS

[amjith]

This adds the option for a user to set up triggers in the database to keep their FTS table in sync with the parent table.

Ref: https://sqlite.org/fts5.html#external_content_and_contentless_tables

I would prefer to make the creation of triggers the default behavior, but that will break existing usage where people have been calling populate_fts after inserting new rows.

I am happy to make changes to the PR as you see fit.

[simonw]

This is brilliant!

One tiny suggestion: I like --create-triggers and create_triggers=True better for this as they are shorter but still capture what it dies - especially since the underlying SQL uses CREATE TRIGGER statements.

[amjith]

I have merged the other PR (#56) into this one.

I have incorporated your suggestions. Cheers!

[simonw]

This is fantastic, thanks so much.

I spotted a Datasette bug triggered by this: Datasette has its own version of the detect_fts function - at https://github.com/simonw/datasette/blob/d224ee2c98ac39c2c6e21a0ac0c62e5c3e1ccd11/datasette/utils/__init__.py#L466-L479 - which fails to pick up FTS tables created using the new escaping pattern.

It's a bug in Datasette, not sqlite-utils - so I'll open an issue there.

[simonw]

Released in 1.11 - thanks again! https://sqlite-utils.readthedocs.io/en/latest/changelog.html#v1-11