* Add comments.
* Implment MSC3873 to handle escaped dots in keys.
* Add some comments about tests.
* Clarify spec behavior.
* Fix typo.
* Don't manually iterate string.
* Clean-up tests.
* Simplify tests.
* Add more tests & fix bug with empty parts.
* Add more edge cases.
* Add a regular expression solution.
This is ~80% slower than the basic split(".").
* Split on a simpler regular expression.
This is ~50% slower than a simple split(".").
* Remove redundant case in regex.
* Enable sticky regex.
* Rollback use of regex.
* Cache values in the PushProcessor.
* Use more each in tests.
* Pre-calculate the key parts instead of caching them.
* Fix typo.
* Switch back to external cache, but clean out obsolete cached values.
* Remove obsolete property.
* Remove more obsolete properties.
