Add getCell and getRandomCell methods

src/main/java/CellSample.java

@@ -49,6 +49,13 @@ public class CellSample {
         return cells;
     }
 
+    public String[] getCell(Integer n) { return cells.get(n); };
+
+    public String[] getRandomCell() {
+        int n = BiGpairSEQ.getRand().nextInt(cells.size());
+        return getCell(n);
+    }
+
     public Integer getCdr1Freq() {
         return cdr1Freq;
     }