Added QB SOUND keyword

[grymmjack]

Added SOUND keyword support with validation and support for additional shapes as provded by the WebAudio API OscillatorNode object.

Validation is based on legal QB SOUND ranges.

Freq: 0 = Delay instead of sound, or 32 to 32767
Shape: default = "square" additional shapes: "sine", "sawtooth", "triangle"

Example code / test:

Sound 100, 100 : Sound 900, 100
Sound 100, 100 : Sound 0, 200 : Sound 800, 300
Sound 0, 500 : Sound 50, 50 : Sound 100, 50

Sound 0, 1000
Sound 800, 100, "triangle"
Sound 0, 500
Sound 1200, 100, "sawtooth"
Sound 2400, 200, "sine"

Sound 9000, 1000
Sound 9000, 1000, "triangle"
Sound 9000, 1000, "sawtooth"
Sound 9000, 1000, "sine"