Some users have subscribed without having commented or voted.  This
added additional complexities as subscription db in mongo lists users by
external_id unlike all other tables which list the username... oh crap.

Refactored things around considerably.  Mongo comments and subscriptions
are now loaded up front, so all following procedures can operate on
them.  Added lots of messy logic into UsersTable, building an additional
index by external_id and looking up usernames from Sencha Forum db by
external_id. Thankfully it's a throw-away script, as the resulting code
is quite fragile and messy.

Also found one user who had subscribed bot no more has an entry in
Sencha Forum database.  Going to throw away his 3 subscriptions.

Plus include all voters to users table - some users have only logged in
to vote - for them the only trace we got is the username in upVotes or
downVotes array.

Generate ID-s for all tables and link users and targets from comments
table by ID-s.

Most comments have both author and userId field, but some earlier
comments lack the latter, so we query the sencha forum database to find
out the ID-s by username.

Also change users.name field to users.username - more clear.

A link to Sencha Forum database.

That field is not used in current comments database, having it
is also a premature optimization.

Because almost all queries need to exclude the deleted comments,
it helps having a view that excludes these.

Instead of two fields 'ext-js' and '4' we can have just 'ext-js-4'.
Simplifies most queries.

Gives much cleaner look to our methods list.  This is also the way how
other JavaScript documentation tools display the method signature.

Ignore statements that don't contain a `return` statement.

This means that now a function that contains just one `return this;` at
the end of itself will be detected as chainable; given there's no other
return statements anywhere in the function body.

Forgot to excercise this code when refactoring the :members structure.

No more simply labeling constructors with "Object" return type -
instead the ReturnValues class assigns the actual class as return type.

Planning to extend its functionality to auto-generation of other return
values too.

As we're only detecting 'return this;' using a predicate is better
than a function returning 'this' or nil.

FunctionAst is now also a singleton, but that fact is hidden away behind
static #chainable? method.

To auto-detect return types of functions from source code.

This version is able to auto-detect if a simple function without any
control flow statements returns this.

When doc-comment contains @return {OwnerClass} this,
automatically add @chainable tag too.

Encapsulate both full metadata rendering and signature rendering inside
it.

Showing the text:

    New since {version}

This is quite a hack, but was really needed. Damn!

A leftover from refactoring.

Easier to just use cls[:name] and keeps JsDuck::Class simpler.

Turns out the short class name is only needed when generating search
data - so no need for the short_name method to be in JsDuck::Class.

Not really a responsibility of the core JsDuck::Class.

The hash is no more needed, we only need to loop through all the types.