Corrected typo.
Added: Methods for equality checking for all data-structures in cl-feature-constraints.
Added copy-function for geometric features.
Added unit-tests package for cl-feature-constriants.
Added: Copy function for feature-relations.
Refactored test-case to use key-arguments of copy-function of geometric-features.
Added unit-tests for basic testing of feature relations.
Added doc-string.
Added: Copy functions for feature-constraints and feature-constraint-states.
Added: Unit-test for basics of feature-constraints.
Bug-fix: Use of correct slot-name.
Further unit-test.