Add water to wetlands

[Matthias84]

Hi, I really love the way how F4 Map renders wetlands as a mix of water and land. This indicates esp. that this area isn't easy to pass and give this landmarks a good to recognize style.

Not sure, if it's nessesary to distinguish reed, woods, ... but yes it's possible and might encourage mappers to add this kind of details :wink: https://wiki.openstreetmap.org/wiki/Tag:natural%3Dwetland