Tweaked GWT reflection

- Added CachedTypeLookup for Class-fields which were often looked up using ReflectionCache.getType
- the get-Method/-Field methods of Type now cache the list of methods/fields so the class hierarchy traversal is only necessary once
- Parameter objects for methods and constructors are now reused in IReflectionCacheGenerated by assigning each unique parameter to a variable which can be used multiple times.
- newArrayC in IReflectionCacheGenerated used another logic for calculating the class name for the lookup.
- the assignable-Set of Type always contained Object.class and the current type's class. This is redundant as this can be checked by comparing the class types. This way for a lot of Types the assignables-Set can be empty.
- Removed an unused Test class