Conflict Resolver API Changes

The current resolver resolves all selectors that match the target block object in the key selector. This means that states targeting that same object get overridden too. That seemed like a good idea, but it turns out to be sub-optimal for many use cases, especially inheritance (which is a resolution abstraction)

A new syntax for resolution is documented in the readme and needs to be implemented.

https://github.com/css-blocks/css-blocks/blob/master/README.md#resolving-state-conflicts