This reverts commit 1a8e823c.

* enable obstacle layers

* We need to re-enable the in_window flag once we get close.

* Ignore y velocity in RotateToGoal critic if differential drive robot.

* Scores need to be positive.

* Fixing linter issue

* Revert "Ignore y velocity in RotateToGoal critic if differential drive robot."

This reverts commit 3fef45d335d4dd9c196331d5aaf931a0cb204f48.

* Make closer goals to robot so it is more inclined to follow the path

* Add some comments

* Fix linter issues.

* Various DWB param tweaks.

* Easing off final positioning parameter

* Increase obstacle avoidance strength

* Removing a parameter that doesn't need so much tweaking.

* Push final pose on trajectory instead of initial pose.

* We need start pose and end pose for trajectory visualization

Also making the same fix in the limited accel generator.

* Fix unit tests

* addressing #591

* Enabling planner tester

* Removed placeholder code for yaml

* Fixed typo

* Disabling test

* Test stubs

* Defining the tests

* Fixed build error

* Fixing test issues

* Renaming task server start and stop

* Creating separate build file for tests

* Addressing feedback

Use the new Coroutine-based BTActionNode base class as that is recommended for ROS Action-like tasks (#492)

* Moving service_client.hpp to nav2_util

The ServiceClient class will be used Lifecycle helper functions that
will be put in nav2_util, so we need it there. It seemed more of utility
class than a Task anyhow.

* Add internal node helper functions.

Add some helper functions for generating node names. These will be used
to fix some potential problems with the ServiceClient and the upcoming
LifecycleServiceClient.

* Add node name filter to ServiceClient.

ServiceClient reuses the service name as the temporary node name.
However, service names frequently have / characters in them and
that is invalid for a node name. Also, it seems likely we'll have
multiple clients using the same service. This would result in a name
collision. This now adds a random suffix to the internal node name.

* Allow ServiceClient to use a passed in node.

ServiceClient can now use a supplied node instead of always creating
it's own. This allows us to create a higher level service client that
interacts with multiple services using just one generated node.

* Add a Lifecycle Service Client.

The unit tests will be handled at a higher level by a subsequent checkin

* Clean up and rename existing string utils module

I need to add another function to it, and it could stand some
restructuring before hand.

* Adding a split function

Adding a function to split a string at delimiters. The intent is to
use this later so tests can get ':' seperated string of lifecycle nodes
from and environment variable, and spin them all up.

* Add helper functions to facilitate bringup lifecycle nodes

* Add simple lifecycle bringup utility.

* Turn helper node into a lifecycle node.

* Add timeouts and retries to service calls.

Service calls still hang for some unknown reason. The only known
fix is to time it out and retry.

* Fixing coding standard violations in nav2_util library.

* Renaming one more function to comply with style guide.

Adding a service definition for clearing the entire costmap.

* Adding documentation to the motion primitives.

Modifications to isStuckCondition node

* Fixing memory leak within costmap2d inflation layer.

* Enable A* and Bt navigator as default.

Also add an A* system test.

* Better way of checking astar bool value

* Revert "Enable A* and Bt navigator as default."

This partially reverts commit 1e06e56d2452b7c9dce51267fec769095ce73d93.

The addition to the system test is left in place, just the change to
the user scripts is removed.

* Add some comments explaining the system test configuration choices

* Workaround for sliding sideways bug

* Adding comments to yaml file.

* Use the new onInit method that's now provided by the BT library; can get rid of our own version

* Enable NavigateToPose as well with onInit

* Clean up ctest retry script to allow running in place.

* Use the new ctest_retry script and retry each test individually.

* Remove colcon version of test retry since we can't get debug output.

* Enable bt navigator system test.

* Add comments to address review issues.

Add docker file that builds against crystal release for use in testing the crystal-devel branch (#562)

* Add docker file that builds against crystal release.

* Need to remove the system_test colcon ignore before running rosdep

* Indent lists 

* Add build ARG to disable system tests

Move ARG insertion after rosdep to preserve more caching layers

* Update entrypoint to primary source workspace

Seems necessary when sourcing a colcon workspace that was first initialized using the debian ros2 install,
as opposed to parent workspace installed from the ros2 nightly fat archives.

* Change base docker to `ros:crystal`

Also
 * fixing a syntax error on if statement
 * moving rm nav2_system_test/COLCON_IGNORE before rosdep call

Update README with the modified turtlebot3 launch file name - https://github.com/ROBOTIS-GIT/turtlebot3/commit/aa5225c7eef9d11924f1fd86a69969e89dab023a#diff-187d6396e5bb42dd1ccfdd9f1a6c4f84 .

Adding a service for clearing a costmap (except some region around the robot)

* Script to generate coverage report. Should be run after test.

* Add helper script for test suite

* Modified travis to use runtestsuite.bash script

* Add coverage to .travis.yml file.

* Add coverage badge to main page

* Run the code coverage report in the docker container.

* Add lcov dependency.

* Trying to add lcov tool to build.

* Add coverage args to build script.

* Fixing passing code coverage args.

* Fixing setting env variable.

* Fixing docker file coverage_enabled flag.

* Fixing coverage report script.

* Pass ci env through to docker

* Fixing the filter rules for this workspace.

* Removing unneeded dependency install line.

* Add comments explaining what lcov lines do.

* Rebasing on top of circle CI and common Cmake functions changes.

* Fixing test suite script name.

* Add codecov to CircleCI jobs

* Add conditional to skip codecov if enable is false

* Remove unnecessary export for codecov

* Update workflow for paralel release and debug jobs

* Forgot to append coverage step to job

* Comment out travis codecove

Fixing the broken build

This reverts commit 97675013, reversing
changes made to 1ae4a549.

Changes are no longer needed since the error this fixed has been turned
into a warning.