* Add support for density compensation

* Fix Documentation and PEP8

* Update to utils.py and README

* Update tests for sensitivity extraction

* remove warning for pyNUFFT and make it an error

* Update based on comments from Zac

* Revert a single change to prevent unwanted changes

* Final changes

* Make den_c None in case not used

* Fix Doc

Co-authored-by: chaithyagr <chaithyagr@gitlab.com>