Michał Kępień authored Mar 13, 2018 and Evan Hunt committed May 10, 2018

Implement dns_test_difffromchanges(), a function which enables preparing
a dns_diff_t structure from a mostly-textual representation of zone
database changes to be applied.  This will improve readability of test
case definitions by allowing contents of a dns_diff_t structure, passed
e.g. to update_sigs(), to be represented in a human-friendly manner.

(cherry picked from commit 3c22af0d)
(cherry picked from commit d4c603eb)
(cherry picked from commit 1f454b8d)
(cherry picked from commit 7193496b)