added test for ptr_eq on fresh_name-generated idents
added gensym_copy mechanism to ensure sharing of pointers in the interner

this makes comparisons constant-time, and enables spelling-comparison
of identifiers, crucial in many parts of resolve.
FIXMES (shouldn't appear in upstream)
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tmp... working on getting resolve to differentiate between hygienic and non-hygienic tables
revert change (merge if it's the right thing to do)
tmp