Move functions and structs to external files.
Move inlined FFI to external files.
Version test bump.
Added wave functions.
Added more checks for private functions.
Added the play_freq method and supporting private methods.
Added some play_freq tests.
Added changes so far for 0.6.0.
Added Dominic Muller as an author.
Removed unnecessary require_relative.
Marked certain constants private.
Added a comment.
added default initial values for waveout structs, additional documentation, added play_freq example in examples file
Merge pull request #1 from RSMP/waveout

play_freq polishing
Updated rake build and install tasks.
consolidated and formatted constants, added tests for new code, refactored variable name for play_freq to make more intuitive sense
Added release date.
Removed rubyforge_project spec, bumped version.
Updated manifest.