Roadmap to first tag (probably `0.0.1`)

[johanmalm]

• Consider wrapping each stack item in a QScrollArea (Evaluate approach for stack growth #69)
• Split setting.h into setting.h and settings.h
• maindialog.cpp ::onApply() get filename in more consistent way
• Set environment variables from setInt() and setStr() functions; instead of using envionrment_set() directly for better control so that for example XCURSOR_SIZE are only written to file if different to default
• Read XKB_DEFAULT_LAYOUT and use that as default if nothing set in environment file
• Use namename format baz.bar.foo instead of /foo/bar/baz so that attributes like <keybind name.action="foo"> are supported
• Considering using QVariant rather than std::variant to void specifying all the types.
• Consider optionally supporting gsettings for setting cursor theme, icon theme and gtk theme (like we did a long time ago) (Remove glib dependency #61)
• Add 'About' stack with /proc/$LABWC_PID/exe -v
• Change user-override message to something more helpful
• Automatically handle the correct rc.xml and environment files based on what the the current instance of labwc is using
  • LABWC_CONFIG_RCXML=/home/johan/.config...:/etc/labwc/rc.xml
  • LABWC_CONFIG_ENVIRONMENT (Parse environment.d directories to be consistent with labwc #67)
• Support using multiple rc.xml/environment files and the --merge-config option
  • LABWC_MERGE_CONFIG
• Settings scope
  • Support keyboard GRP keybind (@johanmalm) (Support setting XKB_DEFAULT_OPTIONS #9)