Working with list version 02 rebased

Hello,

Please cancel my yesterday pull request, I had totally screwed my git tree.

Here is a new cleaner one, with the "one column" scenario mostly solved.
On my pc, a dataframe of 1 column of integers is not working properly : 

x=pd.DataFrame([1, 3 ], columns=['toto'])
sqldf("select  *  from x",locals())