simple pid class ready to import as a source library in ROSMOD

1. In this github repo navigate to releases, right click on pid.zip (not the source code zip!) and select `Copy link address'
2. In a rosmod project, drag in a new source library to the software model
3. Paste the link in the url attribute
4. Name the source library pid

1. Drag the library into the set editor of any component that uses it
2. In the forwards section of the component add #include "pid/pid.h

PID pidObject();
PID pidObject(Kp, Ki, Kd, 0, 0, i_max, i_min);

// double goal = XXX;
pidObject.setPoint(goal);

// double currentValue = XXX;
double output = pidObject.update(currentValue);

// double outputMin = XXX;
// double outputMax = XXX;
pidObject.limitOutput(outputMin, outputMax);