Code cleaning in progress. See details below:

- 80 columns reformatting
- Indentation 2-spaced tabs
- Moved DOXYGEN documentation to header files.
- Removed duplicated code related OpenMP parallelized code
(nldiffusion_functions.cpp)
Worked on AKAZE.h and AKAZE.cpp. 80 column reformating, corrected indentation, moved documentation to header file
Worked on Utils[.h, .cpp]. See below:

Moved documentation to Utils.h
Modularized set of utilities in a separate independent library, some documentation fixes
Typo fix on README.md
Changelog updated