This reverts commits:

c721304a
885d908e
a0909989
fb4ad59d
0a9a67cf
0d1624d4
d018cfd5
0504fdd0
a2fd10fe

Conflicts:

	src/plugins/cpptools/cppcodecompletion.cpp

Reviewed-by: Roberto Raggi

These checks are necessary cause of a recent change in the C++ engine.

Reviewed-by: Roberto Raggi

The helpId was working but the tooltip text was empty.

Reviewed-by: Roberto

replace ExtensionSystem::PluginManager::instance()->getObject<Core::ICore>() by Core::ICore::instance()

forward declaration is sufficient.

It used to be in CppTools, but since the hover handler only makes sense
in the context of the C++ editor, this is a better place.

This change removes a number of wrong usages of the CppModelManager::documents()/document().

Enables F1 for opening their help pages. Seems to work nicely.

The macro tooltip is supposed to be a fallback, since otherwise you
won't be able to see type information for macro parameters.

Reviewed-by: Roberto Raggi