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/mighty.yml

@@ -0,0 +1,46 @@
+name: Mighty
+numvoices: 1
+units:
+    - type: envelope
+      id: 1
+      parameters: {attack: 0, decay: 64, gain: 128, release: 64, stereo: 0, sustain: 64}
+    - type: envelope
+      id: 2
+      parameters: {attack: 0, decay: 88, gain: 128, release: 0, stereo: 0, sustain: 0}
+    - type: send
+      id: 3
+      parameters: {amount: 96, port: 5, sendpop: 1, target: 217}
+    - type: oscillator
+      id: 5
+      parameters: {color: 64, detune: 68, gain: 128, lfo: 0, phase: 0, shape: 64, stereo: 0, transpose: 64, type: 1}
+    - type: oscillator
+      id: 6
+      parameters: {color: 32, detune: 58, gain: 128, lfo: 0, phase: 32, shape: 64, stereo: 0, transpose: 52, type: 1}
+    - type: oscillator
+      id: 217
+      parameters: {color: 128, detune: 62, gain: 32, lfo: 0, phase: 48, shape: 32, stereo: 0, transpose: 88, type: 0}
+    - type: addp
+      id: 218
+      parameters: {stereo: 0}
+    - type: addp
+      id: 219
+      parameters: {stereo: 0}
+    - type: filter
+      id: 10
+      parameters: {bandpass: 0, frequency: 64, highpass: 0, lowpass: 1, negbandpass: 0, neghighpass: 0, resonance: 64, stereo: 0}
+    - type: distort
+      id: 11
+      parameters: {drive: 120, stereo: 0}
+    - type: mulp
+      id: 13
+      parameters: {stereo: 0}
+    - type: delay
+      id: 15
+      parameters: {damp: 64, dry: 96, feedback: 64, notetracking: 0, pregain: 96, stereo: 0}
+      varargs: [224]
+    - type: pan
+      id: 14
+      parameters: {panning: 64, stereo: 0}
+    - type: outaux
+      id: 19
+      parameters: {auxgain: 64, outgain: 64, stereo: 1}