Substantial Number of additional ROS2 Features Implemented on My Fork

[Chootin]

As mentioned in a comment in my now merged pull request #122, I have implemented the following ROS2 features (as of writing) on my fork:

• Exposed clock and time messages for users
• Parameter services and handling
• use_sim_time parameter and time handling
• Timers and the time jump callback
• Fetching of native default QoS Profiles
• Overriding parameters for ros2 launch and ros2 run

These features have all been tested on two machines which are both running Ubuntu 20.04 and ROS2 Foxy. I have also been using them as part of the development of a Unity engine simulation toolkit here at QUT.

My Chootin/ros2_dotnet/dev branch (which contains all these features) is currently up-to-date with ros2_dotnet/main and can be automatically merged, so there should be two ways to contribute the code to the main repository.

1. Make a single pull-request with all the features (this is preferable as there are fixes which are not in-order as I've found issues with my original implementations)
2. Do some cherry picking attempting to isolate features to create sequential pull requests to review one at a time

Any thoughts @hoffmann-stefan or anyone else currently managing this repository?

Cheers, Alec.

[hoffmann-stefan]

Sorry, was a busy week. Hope I get the time to look at your branch next week.

35 changed files with 2427 additions and 277 deletions seems a lot for a singe PR.
I will look at the commits myself and try to do some interactive rebase and cherry-picking if you don't mind. Maybe there is some way to at least separate some of that branch out to it's own PR.

[Chootin]

I have a lot of the work already split out into branches, it might be easier if I try to put some of the later fixes into those. I'll have a go on my end. Feel free to have a go at your end as well and see if we can't find a solution that works well.

[Chootin]

@hoffmann-stefan What do you think of Chootin/ros2_dotnet/upstream_pr1?

It may still be too much; however this branch contains just the features relating to clock, timer, and the related fixes which I think should come first.

Possibly what makes this look a little bigger than it is, is that I added RegisterNativeFunction to DllLoadUtils as I grew tired of making mistakes copy-pasting boilerplate code as I was developing this.

[hoffmann-stefan]

@hoffmann-stefan What do you think of Chootin/ros2_dotnet/upstream_pr1?

@Chootin Jup this branch looks good for the next PR, Thanks :) Could you open it?

[Chootin]

PR is now available #124