Refinements to registry tags

[jkbelcher]

No description provided.

[mcslee]

Made a few changes on top of that:
029d4c8

Don't love maintaining separate mutableTags and tags - just gonna wrap with Collections.unmodifiableList when getTags is called (not often), very cheap/lightweight wrapper to avoid risk of data inconsistency.

Also changed init to use the proper addPattern/addEffect methods, so the default tags are added that way. Avoid the risk of maintaining logic for component registration in two places. Got rid of the fugly static block for List initialization in the process.