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 commit adds the support of the & selector.
This selector is useful to join a subrule with a parent selector.
example:
button {
&:hover {
background-color: red;
}
}
will give
button:hover {
background-color: red;
}