Element offset does not resume responding to style changes after reset from manual adjustment

This seems to have been broken ever since the original 3.0 release, but the problematic code is perhaps hit more often now with some of the recent changes to drag behavior. Here is how to reproduce it in any 3.x version:

1) add fermata to rest in measure 1 of empty score
2) double-click to put in edit mode
3) nudge with arrow keys any amount/direction
4) Esc to leave Edit mode
5) Ctrl+R to reset
6) Format / Style / Fermata
7) change offset

Result: nothing happens. The fermata has been reset to its original offset, but it is now marked NOSTYLE and will no longer respond to changes to the style value. Deleting it and re-adding it will cause it to start responding normally again.

The problem is in Element::endEditDrag(), where we set the new offset with undoChangeProperty() but don't pass in anything as the flags parameter, which causes it to be set to NOSTYLE. Whereas the corresponding code in Element::endDrag() does. So, dragging directly instead of double-clicking then using the arrow keys works. But double-clicking then dragging does not, because that too goes through endEditDrag().

There are other side effects of this problem, such as the fact that the offset now may now get written unnecessarily to the score, and other places in the code that rely on checking isStyled() will fail.