added XSDUtils to convert Resource to XSDDatatype objects
updates in TermMap class
added test for TermMap class
cleaned up ObjectMap and made it inherit from TermMap
created PredicateMap class

This class was introduced since only constant predicates were considered
before.
Cleaned up PredicateObjectMap

- now refers to PredicateMap and ObjectMap objects
- removed useless (and questionable) methods
Added classes representing view definition information

These classes, namely ViewDefinitionInfo and QuadPatternInfo, are
containers that can be filled step-by-step, so they should hold data
gathered during the conversion process.
updates on the actual converter + new tests
now also printing the results ;)
Revert "now also printing the results ;)"

This reverts commit 7f01197c090f46f2763a92a965d706bf3b62cebc.
closes #2

- removed useless statements in the converter class