Adding Opera 11 as a compatible browser for ipython notebook

[jankatins]

I just used opera 11 as a browser with iypthon notebook and it worked.

[minrk]

I have heard that the shift-enter to execute doesn't work properly on Opera. Can you confirm this?

[fperez]

I just installed opera 11 for linux x86-64, and while cell execution works, the rendering is off, as the input/output text is shown in a new line:

[Carreau]

Opera does not support flexible box (yet) as of 11.60

Invalid value for property: display
    display: box;
  --------------^

Can't find any official page as of why, but according to some blog they are waiting for more definitive spec.

[fperez]

Thanks, @Carreau, that looks like the right problem. I'd say then that for now, we should not declare Opera really as compatible, as it looks pretty awful. If others agree, my vote would be for closing this PR then; what do you think @JanSchulz ?

[jankatins]

After seeing that it should not look like that (even if I don't mind...) and especially as I'm using a developer version of opera 12, I've to agree that opera is not completely compatible. Sorry for the noise!

[fperez]

No worries, when 12 comes out we can definitely add it in if it works ok in all respects. Thanks for the interest!

[jankatins]

oups, sorry again: opera 12 (developer build) is also not able to render it as intended. It seems that opera won't be able to render it properly in that release :-(

[fperez]

Well, that's a bummer but at least it's good to know. Thanks!