In most cases, we just want Component<any, Env>. But since it was so
annoying to have always the type Env, we actually used
Component<any,any> everywhere.
With this commit, the generic types have a default (and their order is
swapped), so we can simply use Component in most cases, and
Component<Props> when we want to type the props.
This rev. moves the logic of batching the notifications of changes
occurring in the same microtask tick, from the observer, to the
listeners (the context, and the render function of components).
By doing so in render, we ensure that similar renderings are
batched in a single one, wherever they come from (state change,
store change, direct call...).
Géry Debongnie