lowercase books in docs
lowercasing all of the instances
Fix possible memory leak in `stopListening`, refactor
Refactor, account for double-parse bug in `update`
Merge pull request #2219 from tgriesser/docs-updates

Lowercase books in docs
Refactor `update` to reduce wasted lookups
Merge pull request #2261 from caseywebdev/update

Refactor `update` to reduce wasted lookups
Mention that `parse` receives `options` in docs
Fixed edge-version incompatibility
Fix error callback in localStorage sync
Fix #2269 - clone options before modifying
Really fix #2269, remove circular reference.

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Account for another leak case
Revert "Account for another leak case"

This reverts commit 772a5cd0119672969cd0bb5a7a534bac11b07442.
Revert "Really fix #2269, remove circular reference."

This reverts commit 43544ca59e0c4d9868f8ee5ee52dff0508092938.
Update QUnit, phantomjs.
Fixed to pass with edge version of Underscore

Due to changes in https://github.com/documentcloud/underscore/commit/0ab5bdccd41e55fb02331ec7d2d0053e0bdac9e3 need to fix Backbone.Model test. It would be helpful because some people may use Backbone's unit tests in their Backbone-related projects (plugins for example).
Update due to recomendations
Fixed typo
Tweak language.