Update SongPicker.java

[GrzechuGrek]

• Add: Horde event (having at least 6 monsters in a 16 block range)
• Add: Nether dimension event(there solid music in entire dimension)
• Add: End dimension event(same as above)
• Fix: Rain event - music was stop playing, when player hide under least one block(example leaves of tree), although still rain was present.
• Some minor changes in the night time event, underground event, etc.