Change plate reader/writer to use columns as wells

src/main/java/PlateFileWriter.java

@@ -99,7 +99,7 @@ public class PlateFileWriter {
             else {
                 printer.printComment("Std. dev.: " + stdDev);
             }
-            printer.printRecords(wellsAsStrings);
+            printer.printRecords(rows);
         } catch(IOException ex){
             System.out.println("Could not make new file named "+filename);
             System.err.println(ex);