Update API of PID class

[christophfroehlich]

ros-controls/control_toolbox#246

[codecov]

Codecov Report

Attention: Patch coverage is 60.00000% with 4 lines in your changes missing coverage. Please review.

Project coverage is 84.19%. Comparing base (694d6f1) to head (768689e).

Files with missing lines	Patch %	Lines
pid_controller/src/pid_controller.cpp	25.00%	2 Missing and 1 partial ⚠️
...gripper_controllers/hardware_interface_adapter.hpp	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1437      +/-   ##
==========================================
- Coverage   84.19%   84.19%   -0.01%     
==========================================
  Files         123      123              
  Lines       11322    11322              
  Branches      956      957       +1     
==========================================
- Hits         9533     9532       -1     
  Misses       1473     1473              
- Partials      316      317       +1     

Flag	Coverage Δ
unittests	84.19% <60.00%> (-0.01%)	⬇️

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

Files with missing lines	Coverage Δ
...ory_controller/src/joint_trajectory_controller.cpp	83.86% <100.00%> (-0.03%)	⬇️
...ory_controller/test/test_trajectory_controller.cpp	99.74% <100.00%> (ø)
...gripper_controllers/hardware_interface_adapter.hpp	51.72% <0.00%> (ø)
pid_controller/src/pid_controller.cpp	68.42% <25.00%> (ø)

... and 5 files with indirect coverage changes