Why not set TextScript.Y-offset in define-grobs.scm?

[Joe Neeman]

As far as I can tell, whenever a TextScript object is created, it is
immediately sent to Side_position_interface::set_axis(Y_AXIS). It seems
that it is better to just set Y-offset and side-axis in
define-grobs.scm. Is there a reason this is not done? Same thing applies
to Script.

FWIW, this removes some of the urgency from issue #113 because
TextScript was the main culprit in making the estimates bad and removing
the call to set_axis reduces the chance that a simple-closure will be
involved. (I think I'm also close to a full solution but this is a first
step).