Data loader adjustments

[PeterVennerstrom]

Changed regress range definition from tuple to list. The tuple breaks the code when using a single stride: expanded_regress range = -1, -1 not -1, INF.

Added a setting to create the annotation using all contours. Set to false by default.

Changed get_mask_sample_region and get_sample_region to take self.strides directly.

Added coco_seg_fast to init