Rewhack filefilter.py a lot

Signed-off-by: Dan Mick <dan.mick@inktank.com>
filefilter.py: move things into main() function

Signed-off-by: Dan Mick <dan.mick@inktank.com>
filefilter.py: add deletion from output box

Signed-off-by: Dan Mick <dan.mick@inktank.com>
filefilter.py: unused vars

Signed-off-by: Dan Mick <dan.mick@inktank.com>
filefilter.py: one more test for continguous_ranges()

Signed-off-by: Dan Mick <dan.mick@inktank.com>