Add concept of experimental APIs: they are APIs meant to try out support for use cases we would like to address, but gives flexibility to find the right API interface. As such they are not covered by Semantic Versioning. Several are added to start things off: find, getIndex, getLeaf, getLine, getLines.

• Merge disabling list keyboard shortcut when list format is disabled #1257

Thanks to @haugstrup for your contributions to this release.