Graphics/SymbolEditor master branch updated to KF6/Qt6

[Steve Allewell]

Apologies, I had previously sent this to the kde-i18n-doc mailing list, but realised it should have been kde-devel.



I have pushed the code changes to migrate the SymbolEditor master branch to be KF6/Qt6 only.  I no longer intend to maintain a Qt5 specific branch.

Please update the translations to reflect trunk is kf6, no stable branches required at this time.

Thank you.