Broke out end reads from whole clone extracted sequences

For issue #2850

This won't be testable until we have WS245.

You can test at:
  /species/c_elegans/clone/WRM061cH06#02645--10

You will see a new "End reads" entry in the Overview with links to (typically) paired end reads of a clone.

The Sequences widget should also be updated -- it will now display the actual sequence of the clone. Previously, it would display only the first entry of the array under ?Sequence. This was often just a single end read of the clone.