Datepicker fix

[matthiasgeiger]

Fix for #2403 - and as I was just touching this stuff again: I replaced our custom EasyDateFormat class with a standard DateTimeFormatter

• Change in CHANGELOG.md described
• Tests created for changes
• [ ] Screenshots added (for bigger UI changes)
• Manually tested changed features in running JabRef
• [ ] Check documentation status (Issue created for outdated help page at help.jabref.org?)
• [ ] If you changed the localization: Did you run gradle localizationUpdate?

[lenhard]

Code-wise this looks good! It is nice that we are able to remove the custom date formatter completely (and thus its package also).

I wanted to test this in the UI, but somehow I am unable to configure my JabRef to display the timestamp field in the entry editor.

[koppor]

Documentation at http://help.jabref.org/en/TimeStamp

Does not work with master and v3.8 on my side. v3.7 does not compile any more ("Could not find de.undercouch:citeproc-java:1.0.0-SNAPSHOT"). Does also not work with v3.6.

The solution is to reset the preferences.

Solution works for me. @matthiasgeiger Thank you for the fix.

[mlep]

Does not work for me even after resetting the preferences... (JabRef-3.8.1-dev--snapshot--2016-12-20--master--b655bfd.jar)

[lenhard]

@mlep: After resetting the preferences, the timestamp field appears for me and the datepicker works as desired.

The dev version you mention in your comment is not the most recent one, maybe it did not yet include the fix. Can you try again with JabRef-3.8.1-dev--snapshot--2016-12-20--master--62d55e1.jar

[mlep]

Indeed, the calendar is displayed now.
HOWEVER, the Clear function does not work as expected: the timestamp field is not cleared. If I click on Today, then Clear works.

[lenhard]

@mlep Indeed! Clear only works if a proper date is already in the field. If you insert something else, such as abc, then clear does not work.

@matthiasgeiger Can you please address this? Since this PR is already merged, I guess we need a follow-up PR.

[mlep]

Note: for me, it does not clear even if the field content looks good, like:
timestamp = {2016-10-26},