InfrastructureBlockChecker - WaterChecker

These are a solution for not generating town blocks (street, houses) where a given geography part is not suitable for that. I've added some nice architecture for this: Economics (streets, houses, bridges) can provide a list of Checkers which are used upon generating the town structure in the AbstractInfrastructure class. The Population type also provides a list of checkers that should be scanning the geography at the creation of the Population at the given geography. Those results are stored and upon generating a given size level for the population the unavailable blocks for the given checker types of the Economic are checked and so it wont generate the Economic to unsuitable blocks. Now Rivers and Ocean is no longer overwritten by Residences and EconomicGrounds. But the nice is that Bridges will be able to be built upon the water - later, when we'll have them. :D

Now only a few other bugs till the release...