rtabmap_util tests and doc (#1450)

* Initial tests

* more tests

* More in-depth deskew() testing

* slightly less verbose clamping corruption warning

* added tf buffer related tests

* added remaining tests

* Added rosdoc2, improve tests when we require sync of odom stamp and sensor stamp

* cleanup doc

* fixing ci

* rtabmap_util tests and doc

* Added db_player tests

* Added MapsManager tests

* Added map_assembler tests

* Documenting node first draft

* relative links

* Fixed british->usa english style. Reviewed all md files.

* added link to install ros1

* updated badges

* added Iron

* added ubuntu

* added codecov

* updated coverage ci

* fixing rosdep

* updated ci cov job

* ci bump

* fixing cov ci

* small doc cleanup

.gitignore

@@ -1,6 +1,8 @@
 .pydevproject
 .settings
+.vscode
 __pycache__
 # rosdoc2 build artifacts
 docs_build
 cross_reference
+doc_output