Polymorphism on Finder.find

[ypconstante]

Today Finder.find expects a list of html_node tuples, and returns an HTMLTree and a list of resulting HTMLNode.

To allow the changes for #515, we need to return html_nodes only when we don't need to later use the HTMLTree. If receiving an HTMLTree, Finder.find will return a list of HTMLNode, and if receiving a list of html_nodes the return will be a list of html_nodes.

For now we'll keep building an HTMLTree for the search, but this allow a future change to avoid building the HTMLTree on simple selectors without having to change modules using Finder.

This is a breaking change for projects using Finder.find directly.

[philss]

Hey @ypconstante , thanks for the PR once again! I will hold this for a bit, because I need to release a new version - a patch one. I know Finder is not public API, but just in case I will keep the out of the next version.

I will be back to review it soon :)