Allow parameters with zero values.

### Issue
Parameters with zero values ("0") are evaluated as **false** and therefore filtered away. 

### Example
When cropping images using custom coordinates and the crop should be made from the top left corner both X and Y equal 0. If they are filtered away the crop defaults to the center of the image.

### Solution
My solution was to create a custom array filter allowing zero values as either an integer (0) or a string ("0").

I also improved the filtering of empty parameters and added test_no_empty_options to test parameters with empty and zero values. Running the test was successful.