v0.4.0

• Major mechanics update
  • A component now yields a signal directly instead of a function which produces a signal
    • this prevents a signal from being skipped due to the asynchronous nature of the runtime
  • The Subject class now also allows the nextSignal to be retrieved already
    • this is necessary, for example, in the case of the Children class, where rendering can invalidate the current signal downstream
  • The props of a component may only be primitives (boolean, number, string)
  • The h function is implemented more robustly, has full test coverage, and many bugs have been fixed
  • The h function now uses the key attribute to cache both custom elements as well as intrinsic elements
  • The newly introduced ref function can be used to more conveniently create stable element references declaratively