Fix off-by-one bug with endOfStartLevel replace.

This was causing failures on levels 14 and 17. Verified the fix with a local browser JS change. Tried to load a couple of other levels to make sure I didn't break anything else. The issue here is that inserting startOfStartLevel increases the number of lines in the array.
Merge pull request #137 from calbach/patch-1

Fix off-by-one bug with endOfStartLevel replace.