Added a missing method to GenerationLayer

added the usesResolution() method to GenerationLayer.  The method
returns true if the layer is applicable in the given resolution.
Updated generation skeleton to use Arrays of ints

Generation code does not use a Tilemap internally anymore.  It should
initialize a 2d array of ints, which are the integer tile types that
represent the tiles.  These tile types do not have a 1-1 matching with
tiles, as there can be tile types like GRASS and DIRT, which both map to
the GRASS tile.

Also code was cleaned up in terms of whitespace.
Added some comments and switched to using Vectors

Using vectors instead of arrays in order to be able to use generics.
Merge pull request #2 from Amarcolina/master

Updated generation code