Search notice should be customizable

[cgogolin]

O-3PO displays a notice on the search page about what it means if users cannot find a paper via the search that however claims to have been published by the journal publishing with O-3PO. The display of this mesage can be disabled, but it would be better if the notice could also be customized.

[cgogolin]

@drever, would you be interested in implementing this? What has to be done here is very similar to the email template code. We need a page in the settings through wich the texts displayed on the search page can be customized. There are three different texts:

1. No results were found for a regular search: Tell the user what it can mean if they were unable to find a paper they might have been looking for

2. No results were found for a search initiated via the title_click feature of the Quantum latex template (does Compositionallity have something similar?): Tell the user that the paper whose title was clicked has definitely not been published and what this can mean.

3. Some results were found for a search initiated via the title_click feature of the Quantum latex template (does Compositionallity have something similar?): Tell the user that what it can mean if the the paper whose title was clicked was not actually among those in the list.

Please give me a few days to first merge the improve_settings branch before implementing anything. Probably it would be good if we first have a chat in any case.

[drever]

Sure, let me know when I can start!

[cgogolin]

I merged the last bigger changes I wanted to get into the code base before you start. All ready to go now :-)

Maybe it would be good to move the shortcode expansion code to a separate class, so that both the email template class and the journal class (which is responsible for this search form additions at the moment) can use it. Maybe we even want to move the search form modifications out of the journal class and into the code in o3po/public? Let me know in case you want to have a chat about that.