Concept,Cologex,Goal: refactor headers

All Cologexes (both Cologexes and CologexSets) are now categorized
as Concepts.
Goals are now also Concepts -- they inherit from Concept as a base
class.

Using Concept as the base class for both Cologex and CologexSet
allows us to treat both cologexes and cologexsets the same way
when comparing in the abstract.

smocore/include/concept.h

@@ -0,0 +1,14 @@
+#ifndef _CONCEPT_H
+#define _CONCEPT_H
+
+namespace smo {
+namespace cologex {
+
+class Concept
+{
+};
+
+} // namespace cologex
+} // namespace smo
+
+#endif // _CONCEPT_H