FlxAssetPaths: fix filterExtensions for files with multiple dots (#2107)

Previously getFileReferences filtered extensions using the first string after a dot. This means that myfile.png.old is included even when a filter is set to only import png files. This causes various compiler errors when tortoisesvn is used, due to duplicate file.ext.svn-base files being added. 

New implementation takes the *last* string after a dot, meaning that myfile.png.old is treated as a .old file and will not be included if "old" is not on the filter list.

flixel/system/macros/FlxAssetPaths.hx

@@ -47,7 +47,7 @@ class FlxAssetPaths
 
 				if (filterExtensions != null)
 				{
-					var extension:String = name.split(".")[1]; // get the string after the dot
+					var extension:String = name.split(".").last(); // get the last string with a dot before it
 					if (filterExtensions.indexOf(extension) == -1)
 						continue;
 				}
@@ -83,4 +83,4 @@ private class FileReference
 		this.documentation = "\"" + value + "\" (auto generated).";
 	}
 }
-#end
+#end