This PR was merged into the 1.3 branch.

Discussion
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View Listener

Previously #1062 and #863

TODO

- [x] Documentation

Commits
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fa14af74 Remove incorrect examples and fix grammar
f0d7d7c2 Basic documentation
5407435c Use PHPUnit annotation to skip test on <5.4
b4446482 Document as mixed, may be a string intended to be resolved from the CallbackResolver
f2724fd2 Revert the CS fix and make a valid docComment
ca9fe47b More CS fixes
4e6591c3 CS Fixes
974b49d1 Allow view listeners to be "skipped" by returning null
50150276 Restricted visibility
c86b6f59 Fix docblock type
a7768253 Remove callable hint for 5.3 tests
65a97117 Avoid mutating state
f31bb299 Fix test
3a8e2dd5 Remove callable type hint from chain test for 5.3
a940fbe3 Clarify docblock
0bce9898 Add request to signature to test call
6bddf29e Add ViewListenerWrapper and tests
86c02016 Add view.