This stuff was all over the place, a relic from before the editor
settings were unified. Now the initialization is only done in
TextEditorSettings.

Fixes the .pro file editor and the generic project files editor, which
before only used the font settings.

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

It was getting a bit cluttered without any grouping of the different
actions. Also, the collapse and expand actions have been added, mainly
for discoverability.

Details:  - Naming convention

Details:  - Conform to naming convention

Details:  - To make it conform to naming convention.

support statements later.