speed up the python code for specific area displacement tracking

[Leiguo924]

I know that this repo is not so active now and the contributions are mainly made to the hyp3_autoRIFT now, but it really needs some cleanup and improvements. Since now some parts and functions are quite inefficient. For example, the frequently used colfilt function is very slow especially when deal with the fine-search displacement matrix.

I tried to replace the inside function (e.g. MAD) to the numba implementation, and then colfilt has accelerated for near 300 times (from ~2000 to ~6s)! This is just an example in the code....

My case is obtaining the specific glacier displacement with high resolution, which is different from the original objective for global or large-scale observation, since I used self-customed parameters. And maybe that's why the time is a big issue for me, because for regional study, the parameters are quite large for efficient use.. Nevertheless, this is still important for some specific case studies.

Hope to receive the reply from you!