Unused identifier fixes

[mhegazy]

Fixes #9402 and #9403

We defer checking function expressions and class expressions, and if we want to get the references marked correctly we need to do the reference validation after that is done.

This change refactors the unused local and parameter checking to use a list of deferred nodes to check later.

there are also some bug fixes that i ran into, like not reporting catch variable as unused, reporting unused type aliases, optional parameters, etc..

[vladima]

isReferenced?

[vladima]

LGTM modulo comments

[DickvdBrink]

The code below gives me an error with this branch

tmp/test.ts(5,13): error TS6133: 'initializeInternal' is declared but never used.

If I change it to this.initializeInternal it works. Should I create a new issue for this?

class test {

    private initializeInternal() {
    }

    public test() {
        var x = new test();
        x.initializeInternal();
    }
}

[mhegazy]

thanks @DickvdBrink pushed a fix out in 1fa69ca. can you give this a try?

[mhegazy]

closing and reposting as #9452 to see if travis will pick it up.