TR2 secret issues

[lahm86]

• Incorrect secret order in Floating Islands
  In classic, the stone and jade sprites are swapped to fix this, but this can't yet be done in remastered. Swap the types instead so they appear correctly in-game.
• In 40 Fathoms, the starting area has too much weight so it's generally the case that all three secrets appear before completing half of the level, for example.