Print a message that a function is skipped if a checkpoint file exists.

* Move code that listens to rviz goal_pose message into the NavigateToPoseTask base class
* Fix merge issue and address lint issues
* Remove redundant #include

renamed voxel grid namespace, fixed compiler issues

remove commented out unneccesary code

remove map_msgs package

set dynamic parameters on initialization

adding comment

renable dwbplugin tests

base include in CMakaeLists and first stab port of obstacle layer

continued porting obstacle layer changes

resolving everything for next person except stringstream + message filters issues

add back current amcl changes

add back current dockerfile changes

uncomment arguments in function

* Enable publishing the costmap for debug purposes.

* Changing costmap publishing loop to use std::chrono time

The costmap update loop is using rclcpp::Rate which is always
std::chrono time. The publish cycle should also use that, otherwise
there can be problems getting data published when switching to
sim_time.

* Added an execution timer helper class.

This hides some of the std::chrono manipulation to convert a
duration to a numeric number of seconds.

Also helps to better express why we are measuring time.

* Switching costmap publishing timer to ROS time.

* Check for a switch to sim time and update last_publish accordingly

* Removing unneeded header

* Adding a missed file.

* Getting started; not working yet
* Update the unit test
* Fix issue #44 to modify TaskServer to accept a ROS node rather than be a ROS node

Updated the TaskClient and TaskServer templates to accept a rclcpp::Node::SharedPtr
reference. Also updated the Robot class to do the same. Also had to then change
the execute method to be set on the TaskServer rather than have derived classes
override the method. Now, it is more like the SimpleActionServer from ROS1,
which sets us up a bit better for the port to Actions when ready on ROS2.

* Rename various execute methods to be specific now that they are not overrides of a base class virtual method
* Costmap service name should just be GetCostmap

* Disabling transform timeout

* Adding a comment explaining the TRANSFORM_TIMEOUT and when to remove

* Disabling the costmap movement callback.

This callback produces lots of error message noise. It also has no
actual function and should be removed. It sets a couple of variables
on the costmap object, but nothing actually reads those variables.

* Removing movement callback from costmap_2d_ros

It had no effect. It set variables that were unused in the rest
of the system.

* Wire up the parameter passing in the BT navigator
* Don't change the node name yet; scrub them all later in the same PR
* Work in progress
* Export the nav2_tasks library so that the mission executor can pick it up
* Get rid of duplication in the Behavior Tree-related classes.
* Undo some code that was used for debugging (stubbed dwb)
* Restore file order to be consistent with the BT navigator
* Restore a line inadvertantly removed while using a stubbed debug version of dwb

fix uncrustify & cpplint, changed interface for costmap dynamic params, finish example code, improvements for dynamic params client

* Wire up the parameter passing in the BT navigator
* Don't change the node name yet; scrub them all later in the same PR
* Remove a couple stray printfs from debugging