#17 Add supoprt for xsd:boolean

[Sebastian Trueg]

Virtuoso 6 (as of 6.1.2) does not support xsd:boolean but converts them to int. This is a problem since we are using boolean ranges for certain properties.
Currently Soprano converts booleans into literals with a fake type to prevent the conversion to int. The problem is that this means we have to modify incoming queries by replacing xsd:boolean with the fake type. Without proper query parsing it is impossible to do that without hitting any false-positives.
We cannot change our ontologies to use int instead of boolean since they are public and try to be a standard. That means they have to be backwards compatible and even more important logical. We cannot have a Virtuoso-specific hack in a public ontology.
Thus, this request is for the introduction of native boolean support in Virtuoso.