XPath: Refactor predicate application
XPath: Refactor predicate application

Split number/boolean filtering logic into two functions. This creates an
extra copy of a remove_if-like algorithm, but moves the type check out of
the loop and results in better organized filtering code.

Consolidate test-based dispatch into apply_predicate (which is now a member
function).

zeux/pugixml,zeux/pugixml,zeux/pugixml,zeux/pugixml