Unpack key value tags

Rename "Key:Value" tags to key_value (fruit: lemon -> fruit_lemon)

Converts shapes of classes (e.g. polygon to bitmap) and all corresponding objects

Assigns tags (train/val) to images. Training apps will use these tags to split data.

Merge multiple classes with same shape to a single one

Configure, preview and split images and annotations with sliding window

for both images and their annotations