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

The presets are also organized by their type into subfolders.

Closes #136

tracker/presets/DR/hihat (sample).yml

@@ -0,0 +1,18 @@
+name: hihat (sample)
+numvoices: 1
+units:
+    - type: envelope
+      id: 1078
+      parameters: {attack: 0, decay: 65, gain: 128, release: 0, stereo: 0, sustain: 0}
+    - type: oscillator
+      id: 1079
+      parameters: {color: 57, detune: 64, gain: 128, looplength: 1, loopstart: 1343, phase: 0, samplestart: 367477, shape: 82, stereo: 0, transpose: 70, type: 4}
+    - type: mulp
+      id: 1080
+      parameters: {stereo: 0}
+    - type: pan
+      id: 1081
+      parameters: {panning: 62, stereo: 0}
+    - type: outaux
+      id: 11
+      parameters: {auxgain: 0, outgain: 65, stereo: 1}