Instrumentation: rename "core streaming" to "streams"
streams/stable: detects stable values of a stream over time.
Fix instrumentation test.
Allow tagged-any & tagged-all to be used in where exprs

This change allows the single tag form of tagged-any &
tagged-all to be used in a where predicate expression.

Previously where-rewrite would only recognize tagged.
The logic for all three forms is the same in this case
because it only checks for the existence of a single tag.
Update the docs for tagged-* & where about test exprs

Note that tagged-any & tagged-all can be used in where
test expressions, but only the single tag form.

Testing for a collection of tags is not supported yet.
Merge pull request #227 from samn/where-tagged-rewrite

Allow tagged-any & tagged-all to be used in where exprs
Extract predicate functions from the stream tagged-* fns

Lets the tagged tests be used in where test expressions
without duplicating logic.

Also removes a branch from the stream tagged-* functions
by coercing single tags into a collection before calling
the predicate.
Test collections of tags in where exprs

Lets tagged, tagged-all & tagged-any be used
with multiple tags in the test expression of
a where clause.
Merge pull request #228 from samn/where-tagged-coll

Support for multiple tags in where test expressions