Adding basic files
Adding initial kernel classes
Adding further C++ core code (all untested)
Adding R interface functions
Various neighbourhood calculation fixes
Fixing indexing bug
Adding and using typedefs
Handling 1D input with no "dim" attribute
Fixes to main resampler code
Dealing with requests for a even-width neighbourhood
Making Kernel::evaluate virtual (as it should have been)
Generalising sampling scheme
Fixing problem with my understanding of polymorphism in C++
Exposing a function to R for sampling from a kernel
Adding initial R interface
Adding rescale function to simplify common case of scaling image by a factor
Fixing wrapping, kernel scaling issues in resampler
Switching from size_type to long throughout, since the type is used for (signed) offsets
Simplifying wrap check
Caching kernel evaluations (but lookup overhead is large so this will be reverted)