3.1.6

For RDF::List:

• fix graph used to insert values into a list when not provided.
• use self.class, rather than RDF::List to allow it to be more easily subclassed. (for N3)

For RDF::Query:

• In Query#optimize! partition required from optional patterns so that optional patterns always come last.
• Add Variable#to_base as an alias of #to_s.
• Deprecate Query::Pattern#variable_names.
• Add #var_values and Query::Pattern#var_values to return the appropriate value from a statement (including embedding) associated with that value.
  This abstracts pattern matching to allow for embedded statements, and other things that can be used in a pattern (e.g., lists).

For RDF::Literal:

• Update RDF::Literal::Decimal#round, #floor, #ceil to return integers along with RDF::Literal::Double variations. Previously, they returned the same type.
• Add RDF::Literal::Numberic#** and RDF::Literal::Numeric#% based on XPath definitions.
• Add native support for Rational to xsd:double. Update Literal::Numeric#** to use the type of the native result, rather than always double.

Other:

• Fix bug in vocabulary writer with %() strings.