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.
* Maybe you meant to call base method instead [-Wclazy-skipped-base-method]
* Missing reference in range-for with non trivial type [-Wclazy-range-loop-reference]
* Mixing iterators with const_iterators [-Wclazy-strict-iterators]
* Unused QByteArray [-Wclazy-unused-non-trivial-variable]
* C++11 range-loop might detach Qt container (QList) [-Wclazy-range-loop-detach]
Change Immutable status to ReadOnly, which makes it easy to set value
in script, but still block editing in property view by default. This is
to discourage user editing support using property editor, because
SubShapeBinder requires relative link correction.