astropy/astropy — pull request #438 by wkerzendorf (2012-10-16 16:40:00+00:00)
Title: NDData meta refactor

As previously discussed (#421) here's the refactor of the meta code.

At first I head the following for the `meta`-property:

```python
if isinstance(value, fits.Header):
self._meta = value
else:
self._meta = OrderedDict(value)
```
One needs this otherwise we loose some of the `fits.Header` niceties: `hdr['OBSERVER'] == hdr['ObSeRvEr'] == hdr['observer']` which might be confusing.

But then the problem becomes that we need to check for other possible header structures as well, as they come along.

So for now I just check for `__getitem__` which is a poor mans check. Any ideas?