Add simple (but probably wrong) ordinal axis
Add skeleton for js backend
Remove ArrayDataSource
Play around with template
Add barplot example
Move app-related code out of core-subpackage
Remove `invisible_layout` flag
Replace casuarius with kiwi

Based on Enable commit 2df8c1b96c31fbf4c0a2f1f8fcd58fd866ed1bec
Make backend configuration separate from traits
Make artist responsible for setting the context style
Add simple line-artist test
Add `show` method to generalize app launch
Add app tests based on mock module
Add serialization calls
Add support for serializing Canvas objects
Flesh out serialization using SerializableMixin class
Add some docs
Move serialization code out of plot objects
Refactor serialization to adapter classes
Refactor serialization into modules