#237 Allow import functions to use clipboard not temp files

[Stuart Prescott]

Whenever I download a citation or a set of citations
from a database or from journal's website, I have to
save the citation somewhere (and my browser will
automagically give it some strange name like
uml_view_4.cgi) then use JabRef Import+Append to
navigate to that directory and open the correct file.

Instead, it would be nice to tell my web browser just
to open the file in a text editor (or in the browser
window itself) and then tell JabRef "Import+Append from
Clipboard".

I guess the interface could be somewhat like the "New
Entry from Plain Text" feature (which is a fantastic
feature!) but it would use the existing structured text
importers to automate the process.