Add universal pyfuncs for ROI tiling and object merging

[bwsw]

We meet situations when we want to not scale a frame to the model input but use tiling, when we cover the frame surface with ROIs, matching the model input with overlaps. It allows processing various resolutions without quality decline. Thus, two universal pre-developed functions can be beneficial to end users:

• tile, which creates ROIs
• merge, which merges object ROIs, removes duplicates, and fixes metadata.

The model sits in the middle.