Jsoneditor

- Implemented readonly option for modes `text` and `code.`
Thanks walkerrandolphsmith.
- Upgraded dependencies (`brance` and `ajv`) to the latest versions.
- Fixed not being able to move focus to enum select box when clicking
a JSON Schema warning.
- Fixed 309: already loaded version of Ace being overwritten by the
embedded version of JSONEditor.
- Fixed 368: Mode selection drop down not fully visible on small screen.
- Fixed 253: Optimize the input experience of Chinese IME.
Thanks chinesedfan.

- Fixed embedded version of jsoneditor ace theme not being loaded in
minimalist version (see 55).
- Fixed a styling issue in the SearchBox of Ace editor (mode `code`).
- Fixed 347: CSS more robust against global settings of div position.
- Added docs and example on how to use a custom version of Ace editor.

- Fixed 85: pressing enter in an input in a form containing a JSONEditor too
breaks submitting the form.

- Fixed 329: Editor showing duplicate key warnings for keys defined on the
Object prototype, like `toString` and `watch`.

- Fixed 314: JSON schema validation throwing an error "Unexpected token ' in
JSON at position 0" in specific cases. Thanks apostrophest

- Fixed 308: wrong positioning of label "empty array" when `onEditable`
returns false.