* added a README.md for installation/user guide/procedures
* modified the cuDenseOffsets.py
* expose more options from the CUDA/C++ program
* add an option for varying gross offset input
* clarify the parameter definitions
* removed old SlcImage implementation and cublas dependence
* modified cuSincOversampler
* to be consistent with cpu version
* fix an issue when the extraction of the search window is not around the center
* added a debug mode to output intermediate results
* enable cuda error checking for both Debug/Release build types
* corrected the code to extract raw images when the correlation surface peak is close to edges
* Move utf-8 decoding step inside cython extension
The cython setters take python strings, but the getters return
python bytes, so this makes the types match up. I went with regular
python strings for the interface since they are more common at the
python level, so the encoding/decoding is now an implementation detail
of the cython extension.
Contributed by lijun99, rtburns-jpl, vbrancat, mzzhong