Potential replacement for QSettings. This database will allow us to save
settings incrementially, removing most of the performance issues we're
having when our few megabytes of settings are being saved.

Not done in the form of a QSettings backend because it doesn't seem the
backends can do an incremental update of the settings.

Currently used by the QuickOpenPlugin for testing.

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.

    Details:  access PluginManager::instance() instead

Details: Moving files so that the local layout corresponds to the layout pushed by make install.
Adjust Make target, modify the resource path of the loader to find the resources in the
right place. All pathes are still looked up relative to binaryPath(), libs are found via
relative rpath.

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

Task:     235982

Details:  - Conform to conventions.

Details:  - To make it conform to naming convention.

Details:  - And do some simplification/consistency.