Merge pull request #85 from twmeggs/master

A few clerical corrections to comments and notes within the code.

zipline/transforms/returns.py

@@ -45,7 +45,7 @@ class ReturnsFromPriorClose(object):
     """
     Records the last N closing events for a given security as well as the
     last event for the security.  When we get an event for a new day, we
-    treat the last event seen  as the close for the previous day.
+    treat the last event seen as the close for the previous day.
     """
 
     def __init__(self, window_length):

zipline/transforms/utils.py

@@ -77,7 +77,7 @@ class TransformMeta(type):
     calling Foo(*args, **kwargs) will return StatefulTransform(Foo,
     *args, **kwargs) instead of an instance of Foo. (Note that you can
     still recover an instance of a "raw" Foo by introspecting the
-    resulting StatefulTransform's 'state' field.
+    resulting StatefulTransform's 'state' field.)
     """
 
     def __call__(cls, *args, **kwargs):
@@ -294,7 +294,7 @@ class BatchTransform(EventWindow):
 
         ```
 
-    In you algorithm you would then have to instantiate
+    In your algorithm you would then have to instantiate
     this in the initialize() method:
     ```
     self.my_batch_transform = MyBatchTransform()