Accessor API change. added createAnother functions to NDarray. kslicer.

- Moved Kernel Slicer to slicer.cpp/slicer.h for better maintainability
- Work on Sobel and CollapseSum functions
- changed order of set() functions in accessors classes its now (index, value)
- Simplified copyCast functions, removed unneeded intermediate functions
added new template for the tool for skullstripping