Filter Yoshi

Functional and about as simple as you can get, accepted.

Note that all this code does is set a flag already in the vanilla game, so all the quirks of said flag are still present:

• If the player has Yoshi on the OW, filters Yoshi on level entry, finds another Yoshi in the level, then allows Yoshi to despawn, the player will not have Yoshi upon returning to the OW.
  
  
• If the player has a Yoshi of one color on the OW, filters Yoshi on level entry, jumps onto a Yoshi of a second color in the level, then returns to the OW, the player's Yoshi will be the second color.
  
  
• If a level is set to filter Yoshi, and a Yoshi is then found in said level, moving to a sublevel will filter Yoshi again even if the filter is not set on the sublevel; the Yoshi drums will also play in this sublevel.
  
  
• If filtering a Yoshi when entering a level whose entrance type is "vertical pipe exit down," the player will be displaced an extra tile downward; this can cause a brief graphical twitch when the pipe is close enough to the ground.

Amusingly, you may also choose to filter Yoshi on a level that already has a No Yoshi intro, which makes the automatic movement sequence look stupid on top of being pointless.

Tested with Asar 1.81, Lunar Magic 3.31, SA-1 1.40, Snes9x 1.59.2, UberASM Tool 1.4.

This is the best patch, we will no longer get annoying kill Yoshi and never bring back in level.

Thanks man! I also took a look at your code and it's so simple! I tried the exact same thing with 'init:' and 'main:' but to no avail! Never thought of using 'load:'.