vismach: Fix HalToolCylinder

.. and other subclasses of CoordsBase which do not have any constructor
arguments.
rtapi_math: ensure that isfinite() is available

.. we want it when checking joint positions for sanity
motion: treat a point as out of range when it it is not finite

(not finite includes not only points at infinity, but also points
which are NaNs.  The existing comparisons were enough to weed out
infinities)
motion: check for kinematicsInverse failures

.. and NaN and inf returns of joint positions from kinematicsInverse
kins: Implement linear delta kinematics
vismach: Linear delta visualization
sample-configs: sim linear delta configuration
rtapi_math: fix isfinite implementation for pre-4.4 gcc