Expose full FTS4/5 configuration

[jberkel]

This PR adds support for setting all available parameters for FTS4 with a fluent builder-style interface, #164.

Bonus: Support for FTS5 which differs in a lot of ways from FTS4 but also shares a few config options.

However most users won't need this bit so it might make sense to compile it in conditionally? OTOH it's not a lot of extra code, and pulling in a FTS5-enabled version of SQLite is fairly straightforward now (with CocoaPods / #431).

[stephencelis]

This is really cool! And makes me want to revisit the CREATE TABLE builder for a chained pattern like this.

One consideration I've had for column() options is to use an options set instead of named parameters (since a lot of them are just true or not). Any thoughts on moving that direction? E.g., with your builder pattern applied to the current table builder:

try db.run(users.create()
    .column(id, [.primaryKey])
    .column(name)
    .column(email, [.unique]))

[jberkel]

Good point, that should also simplify the method signatures quite significantly. TableBuilder has currently almost 40 declared public methods.

[stephencelis]

In the spirit of my previous comment, what do you think of updating this to be:

    .column(body, [.unindexed])

[stephencelis]

This is great, thanks again!