Shortcut to call create-element and create functional components

[Deraen]

Currently Reagent has one shortcut to control how components are created:

• :> as shortcut to adapt-react-class which in effect calls create-element and converts the Cljs properties to JS object (doesn't wrap the component in Reagent implementation, so Ratoms won't work inside these components)
• :<> isn't really shortcut, but just special element

I want to add two more:

• Shortcut to call create-element without properties conversion, so Cljs values can be passed to the component as is, without Reagent wrapping the component.
  • Maybe: [:$ react-component #js {:foo "bar" :cljs-vector [1 2 3]}]
• Shortcut to create functional component, same as with the new (r/create-compiler {:functional-components? true}) but without changing the compiler.
  • Not sure what would be good character for this one.
• Wrapping all the function component in Reagent ratom wrapper (the second case) could work for React components also, but is unncessary?
  • These are also wrapped in React/memo as Reagent components are pure, but that might not be the case for React functions?

[Deraen]

Maybe:

• :>> for "raw" create-element call
• :$ for Reagent function component

[minikomi]

Just spitballing - how about keeping the :> class for component generation, but with a tag, eg.

• :r> for "raw" prop passing
• :f> for functional..

Then, it can be easily extended in the future and :<> is just a subset of that class too.

[Deraen]

Nice. We could also deprecate :> (keeps working but prints one deprecation notice) and create named version for that (maybe :a> for "adapt"), or even decide one that automatically converts the props isn't that useful.

[Deraen]

:r> and :f> added to master.

:r> keeps the props as is, but converts the Hiccup children to React elements. Note that props should be JS object ~always (I think) because React crateElement doesn't work otherwise, and React will also add children property to the JS object.