feat(tracker/presets): new and tweaked presets from Reaby

The presets are also organized by their type into subfolders.

Closes #136

tracker/presets/DR/kick test

@@ -0,0 +1,39 @@
+name: Instr
+numvoices: 1
+units:
+    - type: oscillator
+      id: 2
+      parameters: {color: 0, detune: 64, gain: 128, lfo: 1, phase: 0, shape: 48, stereo: 0, transpose: 76, type: 1, unison: 0}
+    - type: send
+      id: 21
+      parameters: {amount: 78, port: 0, sendpop: 0, stereo: 0, target: 12, unit: 0, voice: 0}
+    - type: send
+      id: 22
+      parameters: {amount: 86, port: 4, sendpop: 1, stereo: 0, target: 12, unit: 0, voice: 0}
+    - type: envelope
+      id: 1
+      parameters: {attack: 8, decay: 73, gain: 64, release: 0, stereo: 0, sustain: 0}
+    - type: oscillator
+      id: 12
+      parameters: {color: 128, detune: 62, gain: 128, phase: 0, shape: 60, stereo: 0, transpose: 46, type: 0, unison: 0}
+    - type: mulp
+      id: 14
+      parameters: {stereo: 0}
+    - type: envelope
+      id: 18
+      parameters: {attack: 64, decay: 64, gain: 64, release: 64, stereo: 0, sustain: 64}
+    - type: noise
+      id: 20
+      parameters: {gain: 64, shape: 64, stereo: 0}
+    - type: mulp
+      id: 19
+      parameters: {stereo: 0}
+    - type: addp
+      id: 23
+      parameters: {stereo: 0}
+    - type: pan
+      id: 5
+      parameters: {panning: 64, stereo: 0}
+    - type: outaux
+      id: 6
+      parameters: {auxgain: 0, outgain: 64, stereo: 1}