0.28.0

Includes a wide variety of improvements:

• support currentTime attr of audio/video elements
• support for the files attribute from the target of input elements
• model children are passed to the Javascript mount() function
• began to add tests to client-side javascript
• add a mountLayoutWithWebSocket function to idom-client-react

and breaking changes, the most significant of which are:

• Refactor existing server implementations as functions adhering to a protocol. This greatly simplified much of the code responsible for setting up servers and avoids the use of inheritance.
• Switch to a monorepo-style structure for Javascript enabling a greater separation of concerns and common workspace scripts in package.json.
• Use a loadImportSource() function instead of trying to infer the path to dynamic modules which was brittle and inflexible. Allowing the specific client implementation to discover where "import sources" are located means idom-client-react doesn't need to try and devise a solution that will work for all cases. The fallout from this change is the addition of importSource.sourceType which, for the moment can either be "NAME" or "URL" where the former indicates the client is expected to know where to find a module of that name, and the latter should (usually) be passed on to import()