First draft of ROS Comparison doc

Fixed typo 'an' Task -> 'a' Task

Changed wording from "ROS Navigation" to "ROS1 Navigation"

* Update map_server README
* added issue

* First cut at the Simple Navigatgor README

More clearly called out nav2_bt_navigator and fixed typo

Adding unit test to robot class and disable parsing URDF file

Ability to build Pull Requests in Travis

This is a a workaround. The current AMCL code frequently fails to
transform data and generate a pose. The current hypothesis is that
this is a result of the message filter code having been removed.

This change works around the problem by adding a 1 second timeout
on each transform, meaning there is now a 1 second window from
when the data is received till the transform can become available.

It's not clear whether this workaround has any unintended
consequences. Specfically I'm concerned about performance and
latency.

Parse URDF file from ros_robot class

* changing oregon team email to Carls

* changing header gaurds

* gaurds galore

* Fixing time delays. Duration object takes nanoseconds, not seconds

* Fixing DWB. It runs and almost follows a path.

No pose seems to be available, so it just publishes zero velocity.

* Addressing review comments.

* Provide README for nav2_tasks
* Address review feedback

* Generalize the planning test directory to be a system test directory
* Some updates for the planning tests to adapt to new directory structure
* A bit of reorg on the system test directory per @SteveMacenski's feedback

Fix dockerfile for new repo structure

Instead, we can add the fake_localization package to the repo and
finish the port to ROS2. This will allow us to test the stack with
a stub localizer, thereby avoiding the ros1_bridge when running
in simulation, since AMCL currently needs input from gazebo which
must be run on the ROS1 side since since the ROS2 version of the gazebo
plugins are not yet available.

This problem would cause TaskServer to immediately call the execute
process, even before a command was received. Whether you were
affected by this bug depended on the state of the stack when the
Task Server was constructed.

For some reason, on Ubuntu 18.04, cmath functions are no longer
being added to the global namespace by default. To fix this, the
cmath header needs to be added and the hypot function scoped.

* moved over
* moving all messages into an internal msgs metapackage grouping
* moving all the messages into a homologated package
* making necessary changes for the msgs package homologation
* adding metapackage
* adding  myself as a maintainer
* build script and doc updates for package in workspace
* dealing with merge issues
* remove author fields
* moving around
* merge conflict v3
* remove costmap 2d from utils
* killing src dir
* remove costmap 2d clone #3
* remove extraneous file
* kill dwa for some reason
* dwb rectification
* removing oregon author -> maintainer
* controller -> nav2_controller
* adding new msgs  to new things
* tags
* bringup pkg
* compiling with task status mode
* getting the task status to compile for dwa
* adding costmap2d into nav2 naming nominclature
* adding controller metapackage
* recursive definitions -- bringup cannot be inside of the metapackage
* kill bad line
* hopefully actual last git merge error...
* changelog resolve