[Needs Testing]Added isometric support for tiles

What it says on the tin. I need a tileset that uses the isometric designations to properly test the order of the iso tile pieces.

In the tile_info section of the tileset json there is an optional value "display_type" which is only absolutely necessary if being supplied the value of "isometric". If the tileset is topdown it is not needed since only "isometric" value is being checked for.

Additional subtile definitions for use only in isometric display type:
* "iso_unconnected"
* "iso_center"
* "iso_end_north"
* "iso_end_north"
* "iso_end_north"
* "iso_end_north"
* "iso_edge_ns"
* "iso_edge_ew"
* "iso_corner_nw"
* "iso_corner_ne"
* "iso_corner_se"
* "iso_corner_sw"
* "iso_tcon_north"
* "iso_tcon_east"
* "iso_tcon_south"
* "iso_tcon_west"