One of the features of htm is its ability to let you pass in a class

or function as the tag name, using the following syntax:

`<${MyComponent} foo="bar">...</>


This is useful for letting you reference a class that may be internal or

should otherwise not be registered globally. However, while htm

supported this syntax, Ink didn't know how to handle it.
Now, Ink will take these and construct them, making the assumption that

they are valid component classes. They'll get passed any properties and

children as normal.
Since these don't have registered names, it also means their

subcomponents aren't registered. To allow subcomponent usage, a

subcomponent name can now be prefixed with ., instead of the parent

component name. In this particular case, the subcomponent's full name

and function name will be computed dynamically on use, rather than

during initial registration of the component.
We otherwise still register and look up subcomponents as normal. I had

explored consolidating the logic so that the function name and full name

were always managed at the last possible minute, but that meant that

they couldn't be looked up as possible candidates separate from

components or HTML tags during crafting. It's possible parts of this

will be revisited in the future.

Unit tests pass.
Made use of this in in-progress code in Review Board.