fix code typos

[segasai]

Fix 4 instances of variable names typos in cuts.py (probably most are harmless)

[coveralls]

Coverage remained the same at 57.299% when pulling ed73324 on typo_fixes into 1bf3e0c on master.

[geordie666]

Thanks, Sergey. As you noted, most of these typos are in clauses that we don't actually trigger in the code. Some of the clauses were set up in a certain, formulaic way to facilitate working with mocks as well as with the real data.

The only typo that, I suppose, could have been harmful is the gaiamag = gaiagmag.copy() line. But, I think that will just lead to warnings on comparisons to NaN rather than affecting the actual selection.

In any case, feel free to merge this small PR after documenting it in doc/changes.rst.

[segasai]

Done.
Thanks, Adam.