[CHG] Remove commented out useless code
[CHG] Replaced audio and profile extensions string literals with defines
[CHG] Replaced unsuitable data type in TimerSync
[CHG] Updated mpg123.h to v1.21.0 header
[CHG] Replaced inttypes to r29
[CHG] Removed unused headers in precompiled header
[CHG] Changed license file name from COPYING to LICENSE