fix typos and memory optimisation

Author: vyokky

tensorlayer/layers.py

@@ -1888,7 +1888,10 @@ def __init__(
         Layer.__init__(self, name=name)
         self.inputs = layer.outputs
         self.offset_layer = offset_layer
-
+        
+        if tf.__version__ < "1.4":
+            raise Exception("Deformable CNN layer requires tensrflow 1.4 or higher version")
+            
         print("  [TL] DeformableConv2dLayer %s: shape:%s, act:%s" %
               (self.name, str(shape), act.__name__))
 
@@ -6990,6 +6993,7 @@ def get_batch(self, data, bucket_id, PAD_ID=0, GO_ID=1, EOS_ID=2, UNK_ID=3):
 
 
 
+
 
 
 #