Additions to the island event

[Booplicate]

Additions:

• MASAudioData - isn't used as of now, but will be used later for the next wave of changes

Changes:

• play_song is deprecated in favour of mas_play_song
• various internal functions (island-related) renamed to snake_case to be consistent with the rest of the funcs in the namespace
• backgrounds now properly report which images are missing for which filters
• cleanup of the background framework
• • new internal funcs
• • • getBackground
• • • unlockBackground
• • • lockBackground
• • • isBackgroundUnlocked
• • new global funcs
• • • mas_getCurrentBackgroundId
• • • mas_isBackgroundUnlocked
• background selector was improved
• • we don't suggest to select the current background anymore
• • replaced duplicated code with predicate functions for filtering
• • in case no backgrounds are available, we will show the default as a fallback option (you still can't go into the same background)

Fixes:

• fixed a typo that lead to a name error in _mfwm_find_fb_def

Recognition:

• new deco by @Nemu-sus
• new dlg by @lunulae

Testing:

• verify playing music still works
• verify the background selector still works
• • and you can't go into the same room
• • and current room isn't being suggested
• • and on O31 only the rooms with the required deco are shown
• verify the islands still work
• • test during different time of day (filter) and weather
• • test on O31 (don't forget about the update script)
• • • again, test during the day and night
• • verify your unlocks are valid
• • verify the new dialogue (on click events) is good