Model converters and type-safe events for generated components

New features

• Property-types not supported by the TemplateModel can now be converted using ModelConverters with @Convert-annotation.
• Generated components now support readOnly-properties.
• Events for generated components now support complex object-types.
• Generated listeners now return the correct event-type instead of a generic one.
• Code snippets of generated components are now parsed directly from the source code.
• There is now a project skeleton to be used as a starting-point for new Flow-based applications: https://github.com/vaadin/flow-application-skeleton

Fixes

• Now the generator generates documentation for method call parameters for generated components.
• Inline-resources now work with frontend://-protocol.
• History.pushState and History.replaceState don't reset the scroll position anymore.
• When using @Id, you can use <style>-tags in the template without breaking Flow.

Breaking changes

• TemplateModel doesn't accept empty beans anymore.

Tutorials

• Updated the tutorial about ES5-compilation clarifying the usage of the index.html-file.

All changes

https://github.com/vaadin/flow/milestone/40?closed=1