formatting
Formatting
Remove problematic and maybe unnecessary simplexml_mode test
enable simplexml_mode tests
still run reverse diff test if forward diff fails
Allow disabled:false in tests
Address issue #5 with diff() and php-style gappy arrays

Add testcase (disabled) that elicits issue.  Add parallel testcase with non-index keys that skips issue.

Treat gappy arrays as associative; this solves the gappy-to-whole diff issue, but on the reverse.