store: Apply filters when evaluating attribute values or expressions.
store: Added matchers comparing two expressions.

This is much more powerful than the old conditional matchers and will replace
those once all code has been migrated to the new compare matchers.
store: Added child matchers.

A child matcher matches an object's children of a certain type. It applies
another matcher to all children and matches if any of the children matches.
data: Let sdb_data_parse() support inline casts from string to other types.
store: Added support for regex matchers.

A regex matcher matches the string value an expression evaluates to against a
regular expression. Dynamic regular expressions are supported as well through
expressions evaluating to a string which is then dynamically compiled into a
regular expression when executing the matcher.
store: Added not-equal and not-regex matchers.
data: Don't free memory before using it for the last time.
store: Added sdb_store_parse_matcher_op().

This function parses the string representation of an operator and returns a
constructor for the respective matcher.
frontend: Renamed CONNECTION_EXPR to CONNECTION_MATCHER.

That's more specific.
frontend: Added sdb_fe_parse_expr().

This function enables a special new parser mode in which it only accepts
simple expressions.