- The writer functions have been removed as only used for studying the
behaviour of the filters.
- The documentation of the code was slightly improved.
- Tests for ObservationDataSetUpdate and for the resetFilterNext method
were setup.

- Definition of the AbstractHatchFilter, Doppler, Carrier Phase (Single
Frequency and Divergence Free) Hatch filters, and the associated
PseudoRange smoother classes. An ObservationDataSetUpdate has been
included to allow the filtered data to be carried along with the
original data.
- Definition of the tests.
- The Carrier Phase filters were tested against cases presented in the
gLAB tutorial. The necessary commands and data have been included.

Update .mailmap file

See merge request !232

Thanks to Sofia Urbina for the translation!

fixes #448

Create release from CI

See merge request !210

Conflicts:
	src/main/java/org/orekit/forces/gravity/potential/ICGEMFormatReader.java
	src/test/java/org/orekit/forces/gravity/potential/ICGEMFormatReaderTest.java