Carbohydrates: Refactored glycosidic torsion getters/setters
This push corrects bugs in Pose::phi(), psi(), and omega(), and the cor-
responding setters for carbohydrates. Previously, they did not function prop-
erly in some cases, such as at branches.
I have removed as many uses of strings as I could to improve code efficiency.
I expanded unit tests for sugars.
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Unit test status: Pass
Integration test status: No changes expected