Optional single station coordinate retrieval.

For get_stations_for_event(). Also added a test for the method.
Refactoring.

Replaced all elevation and local_depth with elevation_in_m and
local_depth_in_m.
Refactoring.
Commenting unused part of the code.
Restructuring the validate_data() command.
Bug fix for station file availability
Updating documentation with information about where to find additional
station files.
Documenting project class.
Forget to add project doc
More work on the project documentation
Adding waveform validation ability.

Currently checks that location and the channel type are identical for
one station in one event. This is a surprisingly common source of
errors.
Sorting returned filenames before returning
New class to ease and streamline event handling.

Will be integrated into the project class soon. Will also make the
project class smaller and easier to handle.
Finished the event pseudo dictionary

Also made some preliminary changes to the event class. Will be changed
soon.
Added test that all events are only read once and properly cached in between
Adding get_filename() method to the event pseudo dictionary
Removing the get_filename() method again.

The filename is now, per default part of the returned dictionary. It is
available in any case thus why not pass it on.
Use the new event dictionary throughout the codebase
Some refactoring
Clarifying terminology.