Added HSQL support
HSQL
Merge branch 'feature/hsql' of https://github.com/ontop/ontop into feature/hsql

Conflicts:
	quest-distribution/.settings/org.eclipse.core.resources.prefs
	quest-sparql-compliance/.settings/org.eclipse.core.resources.prefs
	reformulation-core/pom.xml
	reformulation-core/src/main/java/it/unibz/krdb/obda/owlrefplatform/core/Quest.java
	reformulation-core/src/main/java/it/unibz/krdb/obda/owlrefplatform/core/abox/RDBMSSIRepositoryManager.java
	reformulation-core/src/main/java/it/unibz/krdb/obda/owlrefplatform/core/queryevaluation/JDBCUtility.java
	reformulation-core/src/main/java/it/unibz/krdb/obda/owlrefplatform/core/resultset/QuestResultset.java
working on hsql
Merge branch 'feature/leftjoin' into feature/hsql
fix the SQL generator for hsql
correct the JDBCDriver class and Boolean value of HSQL
fix the hsql adapter
fixed Optional-filter