Remove some debug prints, replace them by logging

Signed-off-by: Simon Marchi <simon.marchi@polymtl.ca>
Move rowCount in each item type

Signed-off-by: Simon Marchi <simon.marchi@polymtl.ca>
pep8-ify emissions_treemodel.py

Signed-off-by: Simon Marchi <simon.marchi@polymtl.ca>