Add error threshold to rigid body error graph

[Armita Manafzadeh]

It would be nice to be able to use the same error threshold + "4" hotkey interface that currently exists for reprojection errors also in the rigid body error graph to jump to frames with high error for a selected rigid body.

[Benjamin Knorlein]

fixes #182: Added option to go through Rigid Body Error plot using a threshold

→ <<cset 629c6e620020>>