Various bugs in tutorials

[edderiofer]

See also PR #159, where these bugs were first mentioned.

• Riichi tutorial 2 does not appear to grey out the kuikae 3p.
• Galaxy tutorial 2 takes ages to discard 4s (but not always).
• On my local instance (Windows), Space Mahjong and Galaxy Mahjong have their mods loaded in twice during their tutorials, which cause rules texts to appear twice, and certain yaku to be awarded twice. This only appears to affect these two variants and not Cosmic Riichi or Sanma; and it only affects the tutorials, not the main game mode. (Update: Apparently, this now also affects the site, not just my local instance. I have no clue which commit broke it.)