add WMA algorithm with bitbank bot

algorithm/__init__.py

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+from algorithm.wma    import WMA
+from algorithm.status import Status

algorithm/status.py

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+class Status:
+  def __init__(self):
+    self.price   = 0
+    self.candles = {"1m": [], "1h": []}

algorithm/wma.py

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+class WMA:
+  def __init__(self, unit, period, width):
+    self._unit   = unit
+    self._period = period
+    self._width  = width
+
+  def judge(self, status):
+    cands = status.candles[self._unit]
+    sum = 0
+    den = 0
+    for i in range(min(self._period-1, len(cands)-1)):
+      sum += cands[i+1][3] * (i+1)
+      den += i+1
+    avg   = sum / den
+    price = cands[0][3]
+
+    width = price * self._width
+    diff  = price - avg
+    if diff < 0:
+      return max(-1, diff/width)  # sell
+    else:
+      return min(1, diff/width)  # buy