[Development] All deprecation warnings are P1 for 5.13.0

[Christian Ehrlicher]

Am 09.02.2019 um 10:00 schrieb Allan Sandfeld Jensen:
>> By beta, those that aren't fixed will get P1 bug reports in JIRA.
> By fixed I guess you also mean suppressed were appropriate? some are from
> tests testing deprecated functions, and other are deprecated functions calling
> other deprecated functions because they belong together.
I learned about QT_WARNING_DISABLE_DEPRECATED to work around this e.g. 
here: 
https://codereview.qt-project.org/#/c/252330/3/tests/auto/widgets/itemviews/qlistwidget/tst_qlistwidget.cpp
Not sure if this is feasible for all situations though.

Christian