Clean up existing code and pass jshint

Coding style:
* Avoid meaningless '_' in variable names, especially when used
  inconsistently.
* Avoid trailing line comments.
* Consistent if/else curly brace position.
* Consistently use single quotes (there are no magic quotes in js).
* Consistently use $ in variable names of jQuery-wrapped elements
  (as opposed to plain node references).
* Avoid using variable names like '_this' or 'that', instead name
  them after the object.
* Too many var statements.
* Hoist var statement.
* Fix alignment of closing parentheses in initEditPage.

Code quality:
* Remove commented out code.
* Add missing radix parameter for parseInt.
* Remove unused private function "printWithRunin".
* Remove unused parameters.
* Don't call "console.log" in production client-side code because
  the console doesn't always exist in normal browser modes (and
  would result in an Uncaught ReferenceError, aborting the script
  unexpectedly and leaving the user interface in a likely
  unresponsive state).
* Use the Promise.done and Promise.fail handlers of mw.Api,
  instead of the deprecated 'ok' and 'err' parameters.
* Use jQuery#on instead of the deprecated jQuery#bind.
* Use a local shared reference to the singleton instead of relying
  on 'this' context, this way the methods can be called
  regardless of context. Such as in the $(document).ready(), or
  when passing around setErrors callback.
* Avoid using invalid html shortcuts like <div/>, use <tag>
  for creation, and <tag>..</tag> for parsing (per style guide).
* Document inputKeydown parameter being jQuery.Event (as oppposed
  to native Event).

Misc:
* Renamed '_in' to 'in', and renamed again to 'input' ('in' is an
  illegal variable name and would've crashed).

Change-Id: I283fda1409b1e76db56a939183bdaefc95e60961