A n-dimensional storage structure for Ruby

Manipulating nested arrays in Ruby is a pain and there doesn't seem to be any general purpose solutions (i.e. not math-oriented) available so here is a shot at it.

The idea spawned from trying to map the area around a character in rubywarrior without making any assumption about the size of the map. In other words I needed a 2D array that could grow in any direction. A NArray is a generalization of this idea for an arbitrary number of dimensions. It is similar to a regular array, except you deal with sets of data rather than individual values. E.g. in a 2-dimensional array (a table), you would add and remove rows and columns. The class is a child of Array and responds to #to_ary if one needs to fall back to classic array behaviour (atm work needs to be done to provide a sensible replacement for Enumerator).

Incoming

Tested with minitest 5.9.0