sorry, unimplemented: `method_call_expr' not supported by dump_expr

At the same time, fixed the order in the QuickOpen plugin to make sure
the RefreshInterval setting isn't immediately removed after saving it.

Also disabled debug output for settings database.

Also fixed the restoring of the refresh interval, which was broken due
to different keys being used for saving and restoring.

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.

in place
RevBy:   con

    Details:  failed trial before the committee on un-qtish behaviour

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

forward declaration is sufficient.

Details:  - Naming convention

Details:  - Conform to naming convention

The previous interface wasn't sufficient to properly support the Apply
button, since it didn't separate applying the changes from the cleanup
phase.

Designer settings pages still need some fixing.

Fixes Apply button causing problems for certain plugins, for example the
QuickOpen.

Details:  - Conform to conventions.

Details:  - To make it conform to naming convention.

Details:  - Step one, step two is ActionManagerInterface -->
ActionManager because it conflicts with our naming conventions