Fixed +1 error when sometimes calculating spread

There was a typo in the for loop when looping over the end of the range -- was +1 + 1 instead of just +1.
Added file upload once already uploaded

This way you can add more than one file or add a file after having manually added dragons
Fixed problem with adding manually then adding from file

Problem was with onclick... fixed now, anyway.
Delete all button added

You can now delete all dragons. A warning comes up first, the same as when deleting one.