Allow reading Unspecified type files in WiREReader

[borondics]

Added the Unspecified option to the WiREReaders that allows for readi…ng a file with a single spectrum.

No testing yet.

[borondics]

The problem (I think) is that the unspecified category could be anything.

Should I try to extend this to try all the readers? With several tries or a nested try-try-try?

[markotoplak]

No, don't speculate, just handle what we know there is... So just this for now, and if there is a file where the reader handles and error, well, then we handle that.

[borondics]

So, I found another "unspecified" file that fails for another reason - it seems we have no control over what is in those files. Therefore I came up with this new solution to loop through all readers and check if they can return the structure we expect (at least in case of the single_file for now) or raise some meaningful errors.

[markotoplak]

It is great that you found the file, but still I'd look only use the loop when the type is undefined. Relying on exceptions could be potentially problematic.

I'd have a dict { measurement_type: reading function }, and if the type is defined, just take the correct one, otherwise loop through the values of that dict, as you've done, with exceptions. This would make the could short.