libcore|SavedSession: Record's text formatting expects monospaced fonts
Refactor|libappfw: Item data improvements

- SubmenuItem based on ImageItem
- SubwidgetItem can use a lambda as the widget constructor
- MenuWidget applies the image from any ImageItem
Fixed|libappfw: Popup positioning with Down opening direction

Positioning should not go outside the UI view.
libcore|SavedSession: Adjusted text styling of metadata

Bold for headings, light for titles, regular text for values. Italics
should be used sparingly, if at all.
UI|Client: Use the "Close" icon in various places

The "Close" icon (x) is meant to invoke the roundness of the progress
indicator. The purpose is to add a visual distinction to potentially
destructive actions such as deleting, clearing, and unloading.
UI|Home|Client: Delete savegames via the Game Selection menu/dialog

The saved sessions are now represented in a visually different way in
Game Selection; the visual distinction makes it easier to see the
difference between saved sessions and the other kinds of sessions.

The saved sessions have an X icon that allows deleting the savegame.

Made text styling more consistent in the Home screen info popups
('dimmed' color for paths, bold 'accent' for headings).

There are two variants of the close icon, one without a ring and one
with a ring. These are supposed to be used depending on the context
(e.g., with the ring in menus).

IssueID #1771
UI|SavedSessionMenuWidget: Fixed size of close icon on non-retina displays
Windows|libgui: Emulate light fonts using reduced opacity

Since the light weight fonts are not available in the Windows build,
we can use alpha to emulate the appearance of thinness. This is
important because light fonts are used in the Doomsday UI to convey
information.
Console: Added 'vid-fps' as a mapping for 'Config.window.main.showFps'