Maintenance for Drafts extension

* Replace deprecated calls.
* Update docs.
* Remove some superfluous comments.
* (partial) deglobalization.
* dirname( __FILE__ ) -> __DIR__.
* Bump version.
* Some JS[LH]int suggested updates.

Change-Id: I2148582988e64b5819d5c994a88866e82f3b63b6
Merge "Maintenance for Drafts extension"