Allow ProcessorMotion to produce more than one Feature and Factor

Now PM proceeds like this:

if (new KF) // this condition appears several times in the algorithm of PM.
{
    auto feature = emplaceFeature(cap_current);        // This is pure virtual in PM
    auto factor  = emplaceFactor(feature, cap_origin); // This is pure virtual in PM
}

so only allowing one type of factor.

If a ProcessorMotionDerived wants to add more than one, we need to tweak the two emplace above, and it's not nice.

Examples of PMDerived that might want to do so are:

• ProcessorImu : to create a IMU factor and two Bias drift factors.
• ProcessorForceTorqueInertial : to create a FTI factor, two bias drift factors, and an Angular momentum factor.

The proposal is to substitute the pure virtuals by a single function:

void ProcessorMotion::emplaceFeaturesAndFactors(cap_current, cap_origin) = 0;

so that the piece of algo above becomes

if (new KF) // this condition appears several times in the algorithm of PM.
    emplaceFeaturesAndFactors(cap_current, cap_origin)

EDIT -- click the classes below as they are updated to the new design:

• ProcessorMotion - core
• ProcessorDiffDrive - core
• ProcessorOdom2d - core
• ProcessorOdom3d - core
• ProcessorImu - imu
• ProcessorImu2d - imu
• ProcessorForceTorque - bodydynamics
• ProcessorForceTorqueInertial - bodydynamics
• ProcessorForceTorqueInertialDynamic - bodydynamics

added Agreement required Code organization To Do (release) enhancement labels

assigned to @jsola

created branch 474-allow-processormotion-to-produce-more-than-one-feature-and-factor to address this issue

mentioned in merge request !459 (merged)

changed the description

marked the checklist item ProcessorMotion - core as completed

marked the checklist item ProcessorDiffDrive - core as completed

marked the checklist item ProcessorOdom2d - core as completed

marked the checklist item ProcessorOdom3d - core as completed

marked the checklist item ProcessorForceTorque - bodydynamics as completed

marked the checklist item ProcessorForceTorqueInertial - bodydynamics as completed

marked the checklist item ProcessorForceTorqueInertialDynamic - bodydynamics as completed

marked the checklist item ProcessorForceTorqueInertialDynamic - bodydynamics as incomplete

marked the checklist item ProcessorForceTorqueInertial - bodydynamics as incomplete

marked the checklist item ProcessorForceTorque - bodydynamics as incomplete

marked the checklist item ProcessorImu - imu as completed

marked the checklist item ProcessorImu2d - imu as completed

marked the checklist item ProcessorForceTorque - bodydynamics as completed

marked the checklist item ProcessorForceTorqueInertial - bodydynamics as completed

marked the checklist item ProcessorForceTorqueInertialDynamic - bodydynamics as completed