Fixes: Introduce a cpp settingspage containing file naming conventions (lower case and suffixes). Reorder VCS settings pages.

Task: 241959, 248085

RevBy: Optics/Naming checked by con
Details: Give IOptionPage an id() to differentiate from trName(). Make showOptionsDialog return a bool (applied) and give it an optional parent. Change Cpp and form class wizards, give them a Configure... button to change those settings.

For example when a file was called test.something.cpp, it would search
for test.h instead of test.something.h.

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.