Basic solver result feedback from the mass-spring (cloth/hair) solver.

This returns a general status (success/no-convergence/other) along with
basic statistics (min/max/average) for the error value and the number
of iterations. It allows some general estimation of the simulation
quality and detection of critical settings that could become a problem.
Better visualization and extended feedback can follow later.

source/blender/modifiers/intern/MOD_cloth.c

@@ -179,6 +179,7 @@ static void copyData(ModifierData *md, ModifierData *target)
 	tclmd->point_cache->step = 1;
 	tclmd->clothObject = NULL;
 	tclmd->roots = NULL;
+	tclmd->solver_result = NULL;
 	tclmd->debug_data = NULL;
 }
 
@@ -211,6 +212,9 @@ static void freeData(ModifierData *md)
 		if (clmd->roots)
 			MEM_freeN(clmd->roots);
 		
+		if (clmd->solver_result)
+			MEM_freeN(clmd->solver_result);
+		
 		BKE_sim_debug_data_free(clmd->debug_data);
 	}
 }