restructure bard song stuff -- move song-data class into core, as it
will also be used by structure module in song-block
add prep for sound-block (block based bard...)
more prep work on adding sounds block.  need to add onUpdate and
redstone functionality to TE, and redstone function checkbox to the GUI.
NBT, networking, and GUIs should be otherwise finished.
add functionality to sound block
save out the tune index...just to help with long playlists not
restarting every time the block is reloaded / server restarts