Improvements on CP chart pages

[Sander Roosendaal]

On the OTE ranking page

• sort the pace predictions by duration, shortest to longest, so they're easier to find.
• remove duplicates
• allow deletion of entries

I thought of this because I added a 250m prediction, forgot I'd done so, then added another 250m prediction a few days later. Now I have two such entries at the bottom of the chart and no way to remove either one.