modify extract_simple_patches_2d and reconstruct_from_simple_patches_2d

# Issue Description

`extract_simple_patches_2d` and `reconstruct_from_simple_patches_2d` can not support patches with overlapping. In some cases, overlapping patches is useful.
Hence, we introduce an integer parameter `extraction_step`, and modify these two functions.

* [ ] modify `extract_simple_patches`
* [ ] modify `reconstruct_from_simple_patches_2d`
* [ ] modify unittest