Changes

Add new Quests command (#305)

* Add new Quests command

* Remove class comment
See https://github.com/DenizenScript/Depenizen/pull/305#discussion_r371782981

* Adjust argument prefixes
See https://github.com/DenizenScript/Depenizen/pull/305#discussion_r371783019

* Correct usage
See https://github.com/DenizenScript/Depenizen/pull/305#discussion_r371784344

* Update description
See https://github.com/DenizenScript/Depenizen/pull/305#discussion_r371784852

* Player the person, not Player the object
See https://github.com/DenizenScript/Depenizen/pull/305#discussion_r371785171

* Add error messages
See https://github.com/DenizenScript/Depenizen/pull/305#discussion_r371786529

* Remove comments
See https://github.com/DenizenScript/Depenizen/pull/305#discussion_r371787058

* Use brackets
See https://github.com/DenizenScript/Depenizen/pull/305#discussion_r371787964

* Newline after curly brackets
See https://github.com/DenizenScript/Depenizen/pull/305#discussion_r371788071

* Track throwable
See https://github.com/DenizenScript/Depenizen/pull/305#discussion_r371788214

* Remove whitespace surrounding break
See https://github.com/DenizenScript/Depenizen/pull/305#discussion_r371788387

* Adjust truthiness
See https://github.com/DenizenScript/Depenizen/pull/305#discussion_r371789141

* Better variable name
See https://github.com/DenizenScript/Depenizen/pull/305#discussion_r371790121

* Wrap debug report
See https://github.com/DenizenScript/Depenizen/pull/305#discussion_r371785922

* Vanquish variable
See https://github.com/DenizenScript/Depenizen/pull/305#discussion_r371785993

* Get entry player through utilities
See https://github.com/DenizenScript/Depenizen/pull/305#discussion_r371805722

* Check player elsewhere
See https://github.com/DenizenScript/Depenizen/pull/305#discussion_r371790568

* Change stage_no to stage

* Remove presently unneeded check
See https://github.com/DenizenScript/Depenizen/pull/305#discussion_r371786738

* Use player more
See https://github.com/DenizenScript/Depenizen/pull/305#discussion_r371790121

* Restore debug output
See https://github.com/DenizenScript/Depenizen/pull/305/files/f9894f31455ecc9718312d27b005f71b3b4924f3..29ecc8049088b965ffc67e02ca96168da1187de3#r373830730
 (commit: e5c8932)