test: add unit test for unisons with phase = 0

This demonstrates a bug found by Virgill:
the x86 templates optimize away the phase
modulation when all phases are set to 0,
but the unisons need the phase modulation
internally to offset the phase of the different
unison oscillators.

tests/test_oscillat_unison_phase.yml

@@ -0,0 +1,22 @@
+bpm: 100
+rowsperbeat: 4
+score:
+    rowsperpattern: 16
+    length: 1
+    tracks:
+        - numvoices: 1
+          order: [0]
+          patterns: [[64, 0, 68, 0, 32, 0, 0, 0, 75, 0, 78, 0, 0, 0, 0, 0]]
+patch:
+    - numvoices: 1
+      units:
+        - type: envelope
+          parameters: {attack: 32, decay: 32, gain: 128, release: 64, stereo: 0, sustain: 64}
+        - type: oscillator
+          parameters: {color: 128, detune: 0, gain: 32, lfo: 0, phase: 0, shape: 64, stereo: 0, transpose: 64, type: 1, unison: 3}
+        - type: mulp
+          parameters: {stereo: 0}
+        - type: push
+          parameters: {stereo: 0}
+        - type: out
+          parameters: {gain: 128, stereo: 1}