Python: Run timeline test on differencing input XML

Also implemented a known-good line count check.

Signed-off-by: Alex Nelson <a.nelson@prometheuscomputing.com>
fiwalk.py: Correct Fiwalk fallback call

Signed-off-by: Alex Nelson <a.nelson@prometheuscomputing.com>
Reported-by: Tahir Khan <tkhan6@masonlive.gmu.edu>
Reported-by: Jim Jones <jjonesu@gmu.edu>
Spell out expected delta: elements and attributes
Include validation against baseline DFXML schema
Update DFXML schema to validate idifference output
idifference: Remove redundant annotation

Unfortunately, with namespace issues, the find would fail.

Signed-off-by: Alex Nelson <a.nelson@prometheuscomputing.com>
Merge branch 'master' into delta_schema

Conflicts:
	python/Makefile