Make it easier to import single entries

[tobiasdiez]

Is your suggestion for improvement related to a problem? Please describe.
If you import a single entry (e.g. a bib file containing only one entry), then the import dialog opens and one needs to select the entry by hand, before one can click "Import".

Describe the solution you'd like
Preselect the entry, so that one can directly click "Import".

[P4trice]

PR #5513 sent.

If you have any feedback or issues with it, please tell me.

[tobiasdiez]

Thanks to @P4trice this is now implemented in the latest development version. Could you please check the build from http://builds.jabref.org/master/. Thanks! Please remember to make a backup of your library before trying-out this version.