Coherence Change Detection using Coherence in ifgramStack.h5 (#37)

Add a notebook to do the coherence change detection (CCD) from the coherence stack.

Implemented methods:
+ coherence difference
+ coherence histogram matching
+ coherence ratio

An extra pre-event coherence refinement is implemented on top of the conventional CCD methods.

Author: mgovorcin

README.md

@@ -42,6 +42,7 @@ List of examples of how to build customized application using mintpy modules or
    - Geo / radar coordinates conversion: [nbviewer](https://nbviewer.jupyter.org/github/insarlab/MintPy-tutorial/blob/main/applications/coord_conversion.ipynb)
    - Plot GPS as quiver on top of InSAR data: [nbviewer](https://nbviewer.jupyter.org/github/insarlab/MintPy-tutorial/blob/main/applications/plot_gps_quiver.ipynb)
    - Average velocity estimation demonstration: [nbviewer](https://nbviewer.jupyter.org/github/insarlab/MintPy-tutorial/blob/main/applications/ts2vel.ipynb)
+   - Coherence Change Detection: [nbviewer](https://nbviewer.jupyter.org/github/insarlab/MintPy-tutorial/blob/main/applications/coherence_change_detection.ipynb)
 
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