This patch substitutes by isAttachedToDocument() (almost) everywhere where
getNameInDocument() is used for this purpose.
The very few places not touched by this patch demand a (just a little) less trivial change.
When we change the returning type of getNameInDocument() to std::string,
those places will be easily found, because they shall generate a compiler error
(converting std::string to bool).
Rationale:
The fact that getNameInDocument() return nullptr to indicate
that the object is not attached to a document is responsible for lots of bugs
where the developer does not check for "nullptr".
The idea is to eliminate all those uses of getNameInDocument() and, in the near future,
make getNameInDocument() return always a valid std::string.
* in QtConcurrent::run the order of 1st and 2nd argument are swapped
* QtConcurrent::run asserts that the argument of the passed function pointer is not non-const
* Used methods of QFontDatabase are static in Qt5 and Qt6
* QTextStream::setCodec() has been removed in Qt6
* Argument of enterEvent() has changed from QEvent to QEnterEvent
* QTextCharFormat::setFamily() is deprecated
* Using copy-ctor but class TechDraw::anglePoints has a trivial copy-ctor but non trivial assign operator [-Wclazy-rule-of-two-soft]
* Using copy-ctor but class TechDraw::arcPoints has a trivial copy-ctor but non trivial assign operator [-Wclazy-rule-of-two-soft]
* Missing reference in range-for with non trivial type [-Wclazy-range-loop-reference]
* C++11 range-loop might detach Qt container (QList) [-Wclazy-range-loop-detach]
* signal arguments need to be fully-qualified (TechDrawGui::QGIView instead of QGIView) [-Wclazy-fully-qualified-moc-types]
* Use multi-arg instead [-Wclazy-qstring-arg]
* Use midRef() instead [-Wclazy-qstring-ref]
