Preselect active layer for normalization. Move normalization dialog's logic inside its own init.
Remove numpy dependency; add product and average to zonal statistics when aggregating by zone id
Calculate loss product and average also when aggregating using zonal geometries
fixed error and code cleanup
Merge pull request #25 from gem/preselect-active-layer-for-normalization

Preselect active layer for normalization
Merge pull request #26 from gem/add-prod-and-avg-to-zonal-stats

Add loss product and loss average to zonal statistics
Merge remote-tracking branch 'upstream/master'