removed non-free music.
removed non-free music license
removed music volume preference
v1.4.5-nomusic
(1) rotation button layout changed from vertical to horizontal
(2) overall layout tweaks resulting from (1)
(3) padding between game board and preview window reduced in land mode
(4) game board's squaresize adapts better to screen sizes now
(5) removed music license entry in about menu
(6) removed music attribution note in main activity
v1.5-nomusic
(1) added standard android key press sound
(2) several preference changes and additions
(3) button vibration duration is no longer increased by 5 ms
(4) string changes on account of (2) and (3)
(5) sounds and vibrations are now muteable by global system settings
reworked sound management
without soundpool for now
added Broadcast Receiver to manifest
-> new class for NoiseBroadcastReceiver
changed audio playback method to SoundPool
Merge branch 'master' into nomusic

Conflicts:
	LICENSE.md
again unneccesary
Merge branch 'nomusic'