Nmesh module isn't edges aware yet; but can cause crashes replacing

existing ones that use edges (like when creases or fgons in use).

Added proper free and NULL for it to prevent crashing, rest is for py
team after release ;)

source/blender/python/api2_2x/NMesh.c

@@ -2064,6 +2064,8 @@ static int unlink_existingMeshData( Mesh * mesh )
 	EXPP_unlink_mesh( mesh );
 	if( mesh->mvert )
 		MEM_freeN( mesh->mvert );
+	if( mesh->medge )
+		MEM_freeN( mesh->medge );
 	if( mesh->mface )
 		MEM_freeN( mesh->mface );
 	if( mesh->mcol )
@@ -2171,6 +2173,7 @@ static int convert_NMeshToMesh( Mesh * mesh, BPy_NMesh * nmesh )
 	int i, j;
 
 	mesh->mvert = NULL;
+	mesh->medge = NULL;
 	mesh->mface = NULL;
 	mesh->mcol = NULL;
 	mesh->msticky = NULL;