Added pkgadd distribution for Solaris.

Added a cleaner way to install demo source so that installed versions use a
simplified makedefs/makerules.

Small fix to get osgText to compile with Solaris CC.  Constructor declared
with a non-const argument, but implemented with const argument.

Make/distrules

@@ -1,5 +1,7 @@
 distribution : 
-	@$(MAKEDIST) $(TOPDIR)\
+	@$(MAKEDIST) \
+		$(OS)\
+		$(TOPDIR)\
 		$(INST_LIBS)\
 		$(INST_PLUGINS)\
 		$(INST_INCLUDE)\
@@ -9,3 +11,6 @@ distribution :
 		$(INST_DATA)
 
 	
+
+cleandist:
+	@$(MAKECLEANDIST)