Improve fitting of water to smaller areas

[Nami Verasche]

http://www.lemmingsforums.net/index.php?topic=2728.0

One suggestion is to have smaller copies of the water graphic. A more radical proposal that sounds good but will be tough to implement is to make water resizable.

[Nami Verasche]

Resizable objects (as introduced in commit 147964d) make this redundant.