REL-1308: Made requisite changes to allow for e-offsetting for GMOS N&S ...

...with no guide star if offsets sufficiently small.

Essentially, for GMOS N&S templates, we want to allow for electronic offsetting if there is no guide star but the offsets are sufficiently small (sqrt(p^2 + q^2) <= 1).

I think that the electronic offsetting checkbox behaviour - independent of these changes - needs work, but I'm not going to touch that for now and until it can be discussed in more detail with science staff.