Release v0.0.3

• switched to the fast-opex library
• helper method from_indexedpng was using incorrect label index (off by 1)
• Data.save_image method now ensures that source/target files exist before calling os.path.samefile
• requiring seppl>=0.2.6 now
• readers now support default globs, allowing the user to just specify directories as input (and the default glob gets appended)
• the to-yolo-od writer now has an option for predefined labels (for enforcing label order)
• the to-yolo-od writer now stores the labels/labels_cvs files in the respective output folders rather than using an absolute file name
• the bluechannel/grayscale/indexed-png image segmentation readers/writers can use a value other than 0 now for the background
• split filter has been renamed to split-records