arrayToCSV() fixed for use in Neko 

It seems neko converts Int arithmetic to a Float, which is an invalid accessor for arrays.
alternative version of arrayToCSV() eliminating needless arithmetic

simply has an incrementing array index instead of recalculating it every iteration.

Works fine in the current implementation, though will not work if support is later added for accessing a small square of the provided array
Merge pull request #350 from pentaphobe/flixelNME

FlxTilemap.arrayToCSV() fixed for Neko compatibility