change directory structure, rename array libraries (#87)

lib/python/halo/arrays/distributed/random.py

@@ -0,0 +1,17 @@
+from typing import List
+
+import numpy as np
+import halo.arrays.remote as ra
+import halo
+
+from core import *
+
+@halo.remote([List[int]], [DistArray])
+def normal(shape):
+  num_blocks = DistArray.compute_num_blocks(shape)
+  objrefs = np.empty(num_blocks, dtype=object)
+  for index in np.ndindex(*num_blocks):
+    objrefs[index] = ra.random.normal(DistArray.compute_block_shape(index, shape))
+  result = DistArray()
+  result.construct(shape, objrefs)
+  return result