Add sine waveform
Update copyright year
Fix warnings
Add check if file exists
Add string buffer check
Bump version to 0.4
Exit program if all tracks have stopped
Add --no-time flag
Add --no-sound flag

This implicitly sets --play and --no-time flag
Update exit condition

Exit program is flag --no-sound is set and tracks have repated.
Merge branch 'next'
Bump version to 0.5