Test for yet-to-be-written data retrieval helper function.
Adjusting test
Add ability to get all files for one station from the waveform caches.
Fixing test
Implemented _get_data() method
The Station Cache can now extract coordinates from stations.
Extended the caching.

Now the station information is also cached. Furthermore added some
refactoring.
_get_coordianates_for_channel() method more self-contained
Bugfix station cache.
The station cache now internally caches all coordinates.

Thus, only once per run, the database is accessed for coordinates
extraction purposes. This makes it 4 orders of magnitude faster for only
a limited flexibility loss.
Implementing a certain tolerance to station coordinates
Small changes to the logo
The station coordinates retrieval has been reworked.

It should now support arbitrary types of data and in general be more
consistent.

The waveform caches are now potentially also cached per project
instance. Can be turned off for some queries.