Added tests to Map and Field, fixed an error in UnitTest and DuneClimberTest

src/test/java/bitsplease/mummymayhem/UnitTest.java

...test/java/bitsplease/mummymayhem/model/map/FieldTest.java

src/test/java/bitsplease/mummymayhem/model/map/MapTest.java

...a/bitsplease/mummymayhem/model/units/DuneClimberTest.java

...est/java/bitsplease/mummymayhem/model/units/UnitTest.java