Smoothen Water script should ignore skerries

[Crimsonum]

The Smoothen Water C# script is a great utility, however it has one minor flaw. It doesn't preserve the skerry tiles (water with rocks) which are often used for tactical and decorative purposes. Instead it replaces them with smooth water. Just as the script doesn't touch shores or ice, it should also ignore these tiles.

In Tiberian Sun, the tiles in question are tiles 6, 7 and 13, both in temperate and snow theaters.