This adds a sorted search tree for matchining filters to a template
more efficiently. Each filter is split on "." and each element is
added to the tree. Patterns with matching prefixes are added under
the same subtree.
These are tags that can be added at the template level. They
will override any global tags and any parsed tags with the same
name from the metric will override these.
This filter implementation is fairly naive and won't scale well
to large numbers of templates and filters. It will be replaced
with a trie-based approach in the future.
Jason Wilder