Backport changes from 1.2.0: src/diffpos.c: Handle files with duplicate labels in better - extend generates duplicate labels when it breaks a loop. tests/extend.tst: Enable eswap-break testcase now that diffpos is fixed.
git-svn-id: file:///home/survex-svn/survex/branches/1.0@3705 4b37db11-9a0c-4f06-9ece-9ab7cdaee568