Update colors

Since weekly snapshot 13w42b, the fourth base color variant is multiplied by 135
Fixing color from data values

Using map generated from http://www.minecraftforum.net/topic/661481-windowsmac-version-107-map-item-viewer-editor-and-painter, data values could be negative
Merge pull request #2 from tazorax/master

Fix colors and data values, with many thanks to @tazorax for honouring me by working from my code!