Read from stdio

[ghost]

Allow generating DDL from the output of another command. This should be easy to implement and give a ton of flexibility. "-" seems to be a standard to specify stdin. But it could also be implemented as a command line option.

Two ways I see this being used.

1. A command generates CSV that you want to generate DDL for.:
   getdata -f csv | ddlcreate oracle -

2. Adding a header when the CSV file doesn't include one. We can add a header to the csv via:
   cat header.csv data.csv | ddlcreate oracle -