Move everything to the editor state system

This commit moves everything left out of the previous commit to the
state system. This means a bunch of new functions were added as well,
to avoid the code in each function becoming too huge. A lot of cleanup
was done as well, simplifying logic, merging duplicated code, etc.

This commit does NOT touch "script hooks", script editor logic and
autotiling, as those seem to be their own separate beasts.

desktop_version/src/Game.cpp

@@ -7219,8 +7219,8 @@ void Game::returntoeditor(void)
 
     ed.keydelay = 6;
     ed.settingskey = true;
-    ed.oldnotedelay = 0;
-    ed.notedelay = 0;
+    ed.old_note_timer = 0;
+    ed.note_timer = 0;
     ed.roomnamehide = 0;
 
     // Might've been changed in a script