Release v0.0.7

• added safe_deepcopy method to idc.api._utils which creates a deep copy of an object if not None
• added rgb-to-grayscale filter to convert color images into gray scale ones
• added sort-pixels filter for grayscale images
• the following filters can operate on lists of records now as well: inspec, metadata, metadata-from-name
• added metadata-od filter for filtering object-detection annotations based on their meta-data (e.g., scores from model predictions)
• the filters discard-negatives and discard-invalid-images now output how many were discarded/kept when processing finishes