Studies need to support varying track segmentation parameters

[Thaddeus-Maximus]

This could be accomplished by having prefix segment. before each of the following parameters in a study target :

These are:

• d_nom
• d_scale
• D
• maxcurv
• smoothing
• savgol_amount
• savgol_dof

[Thaddeus-Maximus]

this is done in branch variable_track_smoothing. Note that the product operator cannot be used on track. parameters, however.