RDF/XML files with a UTF-8 BOM fail to parse #187

This patch adds an ad hoc wrapper for streams that strips off UTF8,
UTF16 and UTF32 BOMS. Bit of a kludge to avoid adding a dependency on
Commons classes that do the same job properly. To be changed in version
4 to use Apache Commons.
debug test removed
update versioninfo to 3.5.1
do not actually open a connection to verify if an URL points to an
ontology
drop BOMSafeJavaCharStream fixes #191
Less bytey uncompressed literal impl
OWLLiteralImpl improvements on memory footprint #190

Added special cases for plain literals and xsd:string literals