filters/ccs2ccsflat+ccs_flatten: nothing to do -> return orig. dump

This way, we do not have to bother with stdin and/or magic file
descriptors.  At the cons' side, the equality check is little bit
complicated with a need to normalize both before-after variants,
but this only affects tests anyway (that are accommodating this
change as of now).

Signed-off-by: Jan Pokorný <jpokorny@redhat.com>
Adjust a way to operate in "development" mode wrt. run-dev

Signed-off-by: Jan Pokorný <jpokorny@redhat.com>
tests: add __init__.py to allow custom test picking

Signed-off-by: Jan Pokorný <jpokorny@redhat.com>
run-tests: less verbose, more likely to work with set -e

Signed-off-by: Jan Pokorný <jpokorny@redhat.com>
Expose CLI frontend to be runnable via "python -m" syntax

Signed-off-by: Jan Pokorný <jpokorny@redhat.com>
tests/utils_xml: drop unused import

Signed-off-by: Jan Pokorný <jpokorny@redhat.com>