import-trace: alias-based (importer) registry

This change implements a generic registry in order to clean up import-trace's
code - it's possible (and reasonable) to use the registry for pruners as well.
Importer now extends AliasedRegisterable; all importers have been adapted
to suit the interface/abstract methods.
Each AliasedRegisterable should have at least one alias (the class' name
is a sensible choice) but can have several. The first specified alias is
the class' prime alias which can be used e.g. to list all registered objects.

Change-Id: If6daa34edce35a3b0194e4ba67ed3b44b74a49b0

tools/import-trace/AdvancedMemoryImporter.hpp

@@ -55,6 +55,10 @@ protected:
 	virtual bool handle_mem_event(fail::simtime_t curtime, instruction_count_t instr,
 		Trace_Event &ev);
 	virtual bool trace_end_reached();
+
+	void getAliases(std::deque<std::string> *aliases) {
+		aliases->push_back("AdvancedMemoryImporter");
+	}
 };
 
 #endif