Thanks to Lucian Bărbulescu for the translation!

Fixes #831

Fixes #717

Previously it would fail, now event detection will work, albeit with
some errors due to #834.

Fixes #798

Remove unused imports, fix bug in test where wrong value was used in
assertion.

Also remove Propagator.DEFAULT_LAW. Use IntertialProvider.of(Frame)
instead. See discussion on !189. Part of #586.

Anne-Laure did most of the work to add more informative messages when
root finding for event detection fails. This commit adds a few polishes.
- Added Anne-Laure Lugan as a contributor
- Updated messages to print g values to full precision.
- Made try {} as small as possible since catch() is so broad
- Fix checkstyle warnings
- Add test to check message is formatted correctly

And also the related FieldPropagator.DEFAULT_LAW and
IntertialProvider.EME2000_ALIGNED. Left a couple usages in the tests
that were necesscessary for proper class loading and for testing the
deprecated values. #586

Previously when an analytic propagator handled a continue event the
first part of the step would be passed to the OrekitStepHandler twice.
Now it is only passed once. Seems to have been present when
AbstractAnalyticalPropagator was created, about a decade ago, and not
detected in all the changes since then, so I guess no one uses that
combination much.