libgui|Client: Added rich style 'm' to choose a monospace font
libdeng2|Script|Widgets: Use monospace for 'print' output

Also added a RuleRectangle method for copying another rectangle's
input rules, although this should be used in special circumstances
only.
Console: Added interactive Doomsday Script mode for the command line

Refactored a common base class called CommandWidget for command line
based widgets.

ConsoleCommandWidget handles the execution of console commands.
ScriptCommandWidget has a script context and runs entered scripts in it.

Also applied fixes to LineEditWidget's focus behavior and what
SettingsRegister does when no profiles are available (create a
profile called "Custom" with the current settings).
UI|Renderer Settings: Option to reset the entire profile; UI improvements

The various popup dialogs now use buttons that clearly state the
action to be taken.