Fix key item softlocks

[lahm86]

• Removed room 17 for the red keycard in Diving Area
• Removed room 38 for Key2, Key3 and Puzzle1 in Temple of Xian
• Added return paths to Temple Ruins
• Removed a handful of softlockable locations in Temple Ruins e.g. room 143
• Added a return path to Tinnos to get back across the broken bridge
• Changed each of the element rooms in Tinnos to allow going through them as many times as you like - added pads for the doors instead of them being open by default.
• For the Earth room in Tinnos, an extra path has been added linking rooms 170 and 120, making it easier to get back into the room after the flipmap (only accessible after the flipmap from room 170, so you have to return the intended way initially after getting the mask)
• Moved a softlockable location in Tinnos Earth room 204

I'd like to tidy up the TR2 zoning files, but will do this separately.

Resolves #465.