Add index page title, add mechanism to clear title from defaultRoute.

[askvortsov1]

Fixes #495

Changes proposed in this pull request:
Add index page title, add mechanism to clear title from defaultRoute.

Confirmed

• Frontend changes: tested on a local Flarum installation.
• Backend changes: tests are green (run composer test).

[franzliedke]

Because we now auto-format our JS code with Prettier, this branch now has conflicts with master. Sorry about that. 😉

Please take the steps outlined in the forum to resolve the conflicts.

[clarkwinkelmann]

I believe this PR only changes the behavior on the javascript side, the title on the PHP/preload side will still include the page title?

This does not need to be the same PR, but changing one and not the other wouldn't make sense.

[clarkwinkelmann]

@askvortsov1 what's the plan regarding to my comments above?

Also other comments:

• Should use triple ===
• I think the title count feature should also work on the homepage

[askvortsov1]

Done, all good points. Thanks!

Also, now that Document has access to request, perhaps we should just use the current url for canonical url (in a separate PR)? That's often what we do anyway...

[clarkwinkelmann]

Looking better! Just one question in the comments below.

Also, now that Document has access to request, perhaps we should just use the current url for canonical url (in a separate PR)? That's often what we do anyway...

Definitely something for another issue/PR. I am doubtful that's how we do it.

[clarkwinkelmann]

Yep, I definitely think it's cleaner that way, even though both options would do practically the same.

That way people reading the code don't need to dig into the documentation to find out what originalUri means.