toString() for indexed objects now include their hash code for easy
identification;
random walk test: printing current axioms and taxonomy in the trace
logging
random walk test: forget to remove the fixed seed
Merge branch 'elk-new-incremental' of https://github.com/klinovp/elk.git
into elk-new-incremental

Conflicts:
	elk-reasoner/src/main/java/org/semanticweb/elk/reasoner/stages/IncrementalContextCleaningStage.java