Update README to markdown

Author: superusercode

README

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+# DSP.js
+
+DSP.js is a comprehensive digital signal processing library for javascript. 
+It includes many functions for signal analysis and generation, including 
+Oscillators (sine, saw, square, triangle), Window functions (Hann, Hamming, etc), 
+Envelopes (ADSR), IIR Filters (lowpass, highpass, bandpass, notch), FFT and DFT 
+transforms, Delays, Reverb.
+
+## Modules
+
+* `DFT(bufferSize, sampleRate)`: Discrete Fourier Transform
+  * Usage: 
+    ```js
+    var dft = new DFT(1024, 44100);
+    dft.forward(signal);
+    var spectrum = dft.spectrum;
+    ```
+
+* `FFT(bufferSize, sampleRate)`: Fast Fourier Transform
+  * Usage:
+    ```js
+    var fft = new FFT(2048, 44100);
+    fft.forward(signal);
+    var spectrum = fft.spectrum;
+    ```
+
+* `Oscillator(waveform, frequency, amplitude, bufferSize, sampleRate)`: Signal Generator
+  * Sine wave
+  * Square wave
+  * Saw wave
+  * Triangle wave
+  * Usage:
+    ```js
+    var osc = new Oscillator(SINEWAVE, 440, 1, 2048, 22050);
+    osc.generate();
+    var signal = osc.signal;
+    ```
+
+* `ADSR(attack, decay, sustainLevel, sustain, release, sampleRate)`: Attack-Decay-Sustain-Release Envelope
+  * Usage:
+    ```js
+    var envelope = new ADSR(0.01, 0.1, 0.5, 0.1, 0.2, 44100);
+    envelope.process(signal);
+    ```
+
+* `IIRFilter(filter, cutoff, sampleRate)`: Infinite Impulse Response Filters
+  * Low Pass Filter
+  * High Pass Filter
+  * Usage:
+    ```
+    var filter = IIRFilter(LOWPASS, 200, 44100);
+    filter.process(signal);
+    ```
+
+* `MultiDelay(maxDelayInSamplesSize, delayInSamples, masterVolume, delayVolume)`: Delay which feeds back its own delayed signal	
+  * Usage:
+    ```js
+    var delay = MultiDelay(44100*5, 44100*1, 1.0, 0.6);
+    delay.process(signal);  
+    ```
+
+* `Reverb(maxDelayInSamplesSize, delayInSamples, masterVolume, mixVolume, delayVolume, dampFrequency)`: Reverb
+  * Usage:
+    ```js
+    var reverb = Reverb(20000, 6500, 0.8, 0.5, 0.9, 4500);
+    reverb.process(signal);
+    ```