Merge pull request #4010 from snth/typos

CLN: Added *.dta to the .gitignore. Fixed typo in comment. Removed import.

Author: jreback

.gitignore

@@ -13,6 +13,7 @@ MANIFEST
 *.so
 *.pyd
 *.h5
+*.dta
 pandas/version.py
 doc/source/generated
 doc/source/_static
@@ -33,4 +34,4 @@ pandas/io/*.json
 .idea/libraries/sass_stdlib.xml
 
 .idea/pandas.iml
-.build_cache_dir
+.build_cache_dir

pandas/tseries/offsets.py

@@ -5,7 +5,6 @@
 
 # import after tools, dateutil check
 from dateutil.relativedelta import relativedelta
-import pandas.lib as lib
 import pandas.tslib as tslib
 
 __all__ = ['Day', 'BusinessDay', 'BDay', 'CustomBusinessDay', 'CDay',
@@ -50,7 +49,7 @@ class DateOffset(object):
     is:
 
     def __add__(date):
-      date = rollback(date) # does nothing is date is valid
+      date = rollback(date) # does nothing if date is valid
       return date + <n number of periods>
 
     When a date offset is created for a negitive number of periods,