cacheType [CacheType]:
If true, the floor field will be initialized based on a previously cached version. The
cached floor field will be search at {@link #cacheDir}. The file name of the cached floor
field has two parts: "[cacheDir]/[hash-of-AttributesFloorField-Topography]_[targetId].ffcache"
The hash ensures that only valid version of the cache will be used. If something changed in
the topography or in this attributes settings (except of {@link #cacheDir}) the hash will
differ an a new floor field is created and saved at initialization time.
Thus the created hash file can be moved to a different location without invalidating the
saved floor field.