I think there are problems with having `ccdproc` for the package and `ccdproc` for a module in the package ... I don't remember if they were serious or just confusion by the user.
In any case, I think the convention in Astropy would be to use `ccdproc/core.py` instead of `ccdproc/ccdproc.py` and import anything users are supposed to use into the top-level namespace.