Updated NEWS.txt

NEWS.txt

 .. _NEWS:
 
+Since 0.5rc2
+
+ * Fix a memory leak with shared variable(we kept a pointor to the original value)
+ * The key in our cache now store the hash of constant and not the constant value itself. This is significat for big constant.
+ * theano-cache list list key file bigger then 1M
+ * theano-cache list print an histograme of the number of key per compiled module
+ * theano-cache list print the number of compiled module per op class
+
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 Release Notes
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