#### Is this adding or improving a _feature_ or fixing a _bug_?
Debt.
#### What's the new behavior?
This removes almost all existing deprecations from previous API changes, to save on filesize and reduce complexity in the codebase going forward.
It also changes from using the `slate-dev-logger` to using the Facebook-inspired `slate-dev-warning` which can be compiled out of production builds with [`babel-plugin-dev-expression`](https://github.com/4Catalyzer/babel-plugin-dev-expression) to save even further on file size.
The only deprecations it keeps are in the `fromJSON` methods for data model changes like `.kind` and `.leaves` which may still may not have been migrated in databases, since this is a bigger pain point.
#### Have you checked that...?
* [x] The new code matches the existing patterns and styles.
* [x] The tests pass with `yarn test`.
* [x] The linter passes with `yarn lint`. (Fix errors with `yarn prettier`.)
* [x] The relevant examples still work. (Run examples with `yarn watch`.)
#### Does this fix any issues or need any specific reviewers?
Fixes: #1922Fixes: #2105Fixes: #646Fixes: #2109Fixes: #2107Fixes: #2018
#### Is this adding or improving a _feature_ or fixing a _bug_?
This should fix `Unable to get property 'childNodes' of undefined or null reference` error in IE11 when using slate-html-serializer and deserializing an empty string (#1757, #1756).
#### What's the new behavior?
The `defaultParseHtml` now returns an empty body element if the parsed body is null.
I tested this in the latest Chrome, Firefox and Safari, and they all seemed to work similarly. If the html param was an empty string, `parseFromString` returned a document element, which had a body property which was an empty body element. In IE11 though the body property was null, which caused the undefined or null reference later.
#### Have you checked that...?
* [x] The new code matches the existing patterns and styles.
* [x] The tests pass with `yarn test`.
* [x] The linter passes with `yarn lint`. (Fix errors with `yarn prettier`.)
* [x] The relevant examples still work. (Run examples with `yarn watch`.)
Sometimes, I have nodes that only make sense temporarily, so it
doesn't make sense to serialize them. Following the pattern in React,
explicitly returning `null` from a serialzation rule should result in
that node (and its children) not making it into the serialized document.
* Add Prettier, with basic config and ESLint integration
* Apply Prettier to all files using `yarn lint --fix`
* Tell Prettier to ignore an empty text in a test output.
* Run Prettier on JS files not handled by ESLint, and lint them too
* Implement first working rollup config for main slate pkg
* Convert slate-base64-serializer to rollup
* Convert slate-dev-logger to rollup
* Convert slate-html-serializer to rollup
* Convert slate-hyperscript to rollup
* Convert slate-plain-serializer to rollup
* Convert slate-prop-types to rollup
* Convert (mostly) slate-react to rollup
* Convert slate-simulator to rollup
* Misc cleanup and configuration tweaks/fixes
* Convert slate-schema-violations to rollup
* Successful rollup build for top-level examples
* Add plugin to replace process.env.NODE_ENV
* Only rebuild modules and dev examples in watch mode
* Enable sourcemaps for development builds
* Force debug to use browser version, remove builtins plugin
* Remove is-image from example
It relies on node `path` and wouldn't work well in-browser anyway
* Use browser version of react-dom/server
* Move stray require to import
* Configure examples to watch child package output
* Fix tests
* Remove unneeded preferBuiltins from resolve config
* Use more precise files array to ensure sourcemaps aren't included
* Use lodash instead of lodash.throttle
It's pulled in anyway since slate-react needs slate, so using the
minipackage actually causes code duplication
* Improve naming/fix UMD builds, update UMD doc
* Add rollup configs to linting, add a missing dep to package.json
* Use longform rollup CLI flags
* Add rollup-plugin-auto-external to reduce external module configuration
* Combine rollup config into a unioned helper
* Centralize to a single rollup configuration
* Update dist structure and package field naming for PR feedback
* Add comments and address PR feedback on rollup config
* i.e. -> e.g.
* Add some spacing to the configuration to improve readability
* Add a bit more spacing
* Remove umd from example Slate unpkg link
* rename state to value in slate core, as deprecation
* rename all references to state to value in slate core
* migrate slate-base64-serializer
* migrate slate-html-serializer
* migrate slate-hyperscript
* migrate slate-plain-serializer
* migrate slate-prop-types
* migrate slate-simulator
* fix change.setState compat
* deprecate references to state in slate-react
* remove all references to state in slate-react
* remove `value` and `schema` from props to all components
* fix default renderPlaceholder
* fix tests
* update examples
* update walkthroughs
* update guides
* update reference
`In XML (and XML-based languages such as XHTML), tagName preserves case. On HTML elements in DOM trees flagged as HTML documents, tagName returns the element name in the uppercase form.`
* Fix error when pasted HTML includes a doctype
When pasted HTML includes a doctype definition, `parsed.childNodes[0]`
is the doctype node, not the `<html>` node, so it's not safe to assume
that `parsed.childNodes[0].childNodes[1]` is the `<body>` node.
Using `parsed.body` ensures that we always get the `<body>` node no
matter where it is in the document.
* Update index.js
