Many singletons have their own instance() method, in which case there is
no need to use ICore::instance() to get access to them.

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

forward declaration is sufficient.

Details:  - Naming convention

Details:  - Conform to naming convention

Details:  - To make it conform to naming convention.

Task:     - 237723
Details:  - Look in the same directory first, then go through project's
files.

Some people don't like this.

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.

Save settings instead of crashing. Sorry about that!

It is now possible to choose between case-sensitive or case-insensitive
completion. Also, you can now disable the automatic insertion of braces.

To match the class name, CppToolsPlugin.

In the GUI this is currently called "Methods" with the shortcut 'm'.

Invokable with 'c', currently shows all classes it can find.