Add standalone version of LPF (#164)

[roncapat]

Closes #164.
Test passes locally.

The old LowPassFilter class is now LowPassFilterRos.
API-breaking since with this patch LowPassFilter is a parent class without ROS parameters.

@christophfroehlich at least for now I wanted to reflect the same difference of Pid and PidROS. But we need to devise a different naming strategy, or this patch will break a lot of perfectly fine code (will require people to swap LowPassFilter with LowPassFilterRos in their projects).

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 64.58333% with 17 lines in your changes missing coverage. Please review.

Project coverage is 50.69%. Comparing base (e05102c) to head (7aa2f97).

Files with missing lines	Patch %	Lines
include/control_filters/low_pass_filter_ros.hpp	57.50%	14 Missing and 3 partials ⚠️

Additional details and impacted files

@@               Coverage Diff               @@
##           ros2-master     #192      +/-   ##
===============================================
+ Coverage        50.41%   50.69%   +0.27%     
===============================================
  Files                9       10       +1     
  Lines              486      507      +21     
  Branches            62       64       +2     
===============================================
+ Hits               245      257      +12     
- Misses             215      223       +8     
- Partials            26       27       +1     

Flag	Coverage Δ
unittests	50.69% <64.58%> (+0.27%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
include/control_filters/low_pass_filter.hpp	78.26% <100.00%> (+5.95%)	⬆️
include/control_filters/low_pass_filter_ros.hpp	57.50% <57.50%> (ø)

[christophfroehlich]

Sorry for the late reply. I see two options:

• Use a consistent nomenclature and break API with Jazzy (we would have to branch this repo then)
• Deprecate the old LowPassFilter with the hint to replace it with LowPassFilterRos and call the base filter LowPassFilterBase or similar. This could be then rewritten in a future release to converge back to the consistent nomenclature.

What do you think?

[roncapat]

Sorry for the late reply. I see two options:

• Use a consistent nomenclature and break API with Jazzy (we would have to branch this repo then)
• Deprecate the old LowPassFilter with the hint to replace it with LowPassFilterRos and call the base filter LowPassFilterBase or similar. This could be then rewritten in a future release to converge back to the consistent nomenclature.

What do you think?

Yeah I believe we should slowly make nomenclature consistent, I like better solution 2.

BTW, why are there no 'humble', 'iron', 'rolling' branches and so on in this repo?

[roncapat]

I will update the PR as soon as possible implementing what you proposed as option 2.

[christophfroehlich]

BTW, why are there no 'humble', 'iron', 'rolling' branches and so on in this repo?

because the ros2-master branch is released to all distros, there was no need for branching yet

[christophfroehlich]

@roncapat do you still plan to work on this PR?

[roncapat]

@christophfroehlich sorry but at least for now I'm not able to finish this one due of lack of time. Of course more than happy if someone else can pick this up.