Merge pull request #165 from OpenPIV/optional_normalize_intensity

0.23.1 new features and bug fixes

Author: alexlib

CHANGES.txt

@@ -6,3 +6,6 @@ v0.18  Aug. 8, 2014 -- small updates to the tutorial-part1, MANIFEST.IN, readme
 ...
 v0.22.3 Sep. 22, 2020 -- @erfan-mtr added two-phase extension, see phase_separation.ipynb for the demo
 v0.22.4 Nov, 2020 -- windef refactoring : no more process.pyx, everything in pyprocess.py, numpy vectorized correlation version from windef moved to pyprocess, get_field_shape has less arguments (it's a backward compatability problem, it breaks stuff), new tests, new documentation settings with Jupyter notebook and markdown inserts, tools.save requires also sig2noise column, as in windef, frame_interpolation is now deform_windows with optionaly kx,ky, 
+v0.23.0 - refactored windef.py, with the main functions moved to pyprocess.py
+v0.23.1 - fixed bugs in 0.23.0, new normalized_correlation, normalize_intensity, find_subpixel_position, new tests, new jupyter notebooks, see also 
+            test_robustness