Initial commit for N-Dimensional linked lists.

This is a real implementation, not some shoddy list of lists approach.
test.cpp contains an example.
What it does:
Fill from (0, 0, 0) => (4, 4, 4) in shortest path mode
Then fill again from (4, 4, 4) => (8, 8, 8)
Looking kinda like this:
     /
   _|
  /
_|

Instead of:
    /
   /
  |
__|