Add MentalExistent hierarchy of classes.

These differ from the MentalEntity class hierarchy in that
MentalExistents are a narrower subset of MentalEntities. MentalEntities
refer to all mental content that needs to be persistently stored to
represent cognitive and personna state.

MentalExistents are content of the mind that specifically represents
existents. I.e: perceptual data, whether structural or implicative.

smocore/include/artificedMentalExistent.h

@@ -0,0 +1,31 @@
+#ifndef _ARTIFICED_MENTAL_EXISTENT_H
+#define _ARTIFICED_MENTAL_EXISTENT_H
+
+#include "mentalExistent.h"
+
+namespace smo {
+
+class FogArtificedMentalExistent
+: public ArtificedMentalExistent
+{
+};
+
+typedef FogArtificedMentalExistent Fogaxent, FogArtixent;
+
+class IdyllicArtificedMentalExistent
+: public ArtificedMentalExistent
+{
+};
+
+typedef IdyllicArtificedMentalExistent Idyllixent, IdyllArtixent;
+
+class FantasyArtificedMentalExistent
+: public ArtificedMentalExistent
+{
+};
+
+typedef FantasyArtificedMentalExistent Fantaxent, FanArtixent;
+
+} // namespace smo
+
+#endif