Many changes on explain.depesz.com

Some time ago Eugen Konkov mailed me that he'd like to have some changes on explain.depesz.com.

One of the changes was actual bug, but the rest were improvements to functionality.

I kinda didn't want to do it, but when I looked closer it appeared to me that there are some subtle bugs, and when I'll be fixing them, I can add some of the things Eugen requested:

Starting with added functionality. Please open these links:

Next, in the text and source tabs, there is now button, below text, to copy it to clipboard.

If plan contains nodes that have Rows Removed by … information, this is now shows in rows column, including standard colors if there were more rows removed than returned.

While working on these fixes I found inconsistency. When we had node with more than 1 loops or workers, the site was multiplying time columns based on how many loops or workers there were. But I didn't do it when I was displaying row counts.

For example: this plan, in line 4, shows that Seq Scan returned 113 rows, and 292 were filtered. But this is average over 2 loops. So numbers in rows column should be multiplied accordingly. And now they are.

Additionally, I updated help page, and made column headers in html view link to column description in there.

That's all. I hope you'll find it useful.