feat(tracker): add menu to load instrument presets

The presets are embedded in the executable, so there's no additional files.

Closes #91

tracker/presets/organ.yml

@@ -0,0 +1,33 @@
+name: Organ
+numvoices: 1
+units:
+    - type: envelope
+      id: 1
+      parameters: {attack: 0, decay: 64, gain: 128, release: 64, stereo: 0, sustain: 96}
+    - type: oscillator
+      id: 2
+      parameters: {color: 16, detune: 64, gain: 128, lfo: 0, phase: 64, shape: 64, stereo: 0, transpose: 64, type: 1}
+    - type: oscillator
+      id: 3
+      parameters: {color: 128, detune: 64, gain: 16, lfo: 0, phase: 64, shape: 16, stereo: 0, transpose: 112, type: 0}
+    - type: oscillator
+      id: 4
+      parameters: {color: 128, detune: 64, gain: 32, lfo: 0, phase: 64, shape: 32, stereo: 0, transpose: 88, type: 0}
+    - type: filter
+      id: 5
+      parameters: {bandpass: 0, frequency: 100, highpass: 0, lowpass: 1, negbandpass: 0, neghighpass: 0, resonance: 128, stereo: 0}
+    - type: addp
+      id: 6
+      parameters: {stereo: 0}
+    - type: addp
+      id: 162
+      parameters: {stereo: 0}
+    - type: mulp
+      id: 163
+      parameters: {stereo: 0}
+    - type: pan
+      id: 164
+      parameters: {panning: 64, stereo: 0}
+    - type: outaux
+      id: 10
+      parameters: {auxgain: 128, outgain: 0, stereo: 1}