* Added (receiver|sender)_coverage_statistics, renamed sender_direction_statistics -> direction_statistics, deleted relation_statistics
* Changed index for more performance on date+receiver_id|sender_id queries
* Added FlatCoverageStatistic
* Added max_signal_quality, min_altitude and max_altitude to (Flat|Receiver|Signal)CoverageStatistic
* Renamed FlatCoverageStatistic to AggregateCoverageStatistic
* Make filter more sloppy (error_count from max. 4 to max 9)
* Updated readme
* fixed import
* Bugfix: wrong constraint name
Meisterschueler