Running the OnExitGame and OnLoadGame Hooks fixes some interactions this menu had on the Check Tracker and the Available Checks system.
OnLoadGame overwrote the menu's changes to the next entrance override which were needed for Return to Spawn to work correctly, so I needed to add a new gSaveContext flag for it so that the menu code can set the spawn entrance after all the other entrance overriding code has executed. This also allows any future changes to `Entrance_SetSavewarpEntrance` to take effect when using this menu.

Rewrite Gfx_TexScrollEx / Gfx_TwoTexScrollEx / Gfx_TwoTexScrollEnvColorEx to
emit one command per tile instead of one baked tile size per interpolated frame,
so texture DL memory no longer scales with InterpolationFPS

    Allow player to try opening doors while climbing. Player can't open anything if a door doesn't offer it, so it's ok to try. Handle doors don't change player y position (player walks in the air), so manually lower it.
    Increase y height limit for doors to offer open from 15.0f/20.0f to 50.0f (normal door height). (For shutter doors height could be individualized depending on shutter door type in the future.)
    Make climbing up animation play even for sloped ledges. The animation/action breaks because game thinks player is not on ground. So, at the end of Player_ProcessSceneCollision, if player is in climbing up action, manually set BGCHECKFLAG_GROUND.

Rename various variables across codebase to match decomp,
many had been renamed when exposed for previous save state mechanism