Update grammer to simplify SolutionModifier.
Added #merge! to Prefix to allow for use within grammar parsing.
Fix BNode and Prefix generation.
Force input encoding to UTF-8.
Remove SPARQL 1.0 BNF and parser bits; now only use SPARQL 1.1 grammar, although only 1.0 compatible expressions are handled.

Backawards compatibility issue: Decimal numbers with a trailing "." are no longer supported. Decimals must have at least one digit trailing the "."; this is per SPARQL 1.1 and RDF 1.1 requirements.
Change resolve_uris option to resolve_iris, and add #resolve_iris? accessor.
BNode objects aparently need to have white-space before a closing "." in SPARQL 1.1.
Make two tests (Basic -6/7) not fail; they use decimals with a trailing ".", which is no longer legal.