restructure gem with Library as an intermediate module between Device class and the platform libraries needed to interact with system devices
remove useless wave_data file and rename device_interface to library
rename DeviceInterface::Base to Library::Base and move it to the correct directory
rename DeviceInterface::ALSA to Library::ALSA and move it to the correct directory
rename DeviceInterface::Win32 to Library::MMLib and move it to the correct directory
restructure code. add some device specs