Implements a deep copy of a REGEX object.
| copy-regex < alternation > |
| copy-regex < anchor > |
| copy-regex < back-reference > |
| copy-regex < branch > |
| copy-regex < char-class > |
| copy-regex < everything > |
| copy-regex < filter > |
| copy-regex < lookahead > |
| copy-regex < lookbehind > |
| copy-regex < register > |
| copy-regex < repetition > |
| copy-regex < seq > |
| copy-regex < standalone > |
| copy-regex < str > |
| copy-regex < void > |
| copy-regex < word-boundary > |