Merge pull request #2 from MrSchneepflug/master

Readme and fields
Update Tile.java
Update DisplayGrid.java
Merge pull request #3 from MrSchneepflug/master

Updated Field, Land and Ocean
Update MainClass.java
fixed missing import
fixed Random-object creation
added ocean logic
Added new static method for grid-creation (wip)
Merged Thomas changes, resolved conflicts and cleaned up