CLI options for GUI

[gwennlbh]

Used to:

• Start in specific tab (--tab=TabName (no effect if ui_state.editingworkid is empty), --edit=EditingWorkID (also sets --tab=editor))
• Start with specific settings (--settings=SettingsFile, --settings.Key=Value to override specific settings, --projects=ProjectsFolder as an alias to --settings.projectsfolder=ProjectsFolder)
• Start with specific UI state (--state=UIStateFile, --state.Key=Value to override specific state values)
• Get a setting / ui state (--setting.SettingKey, --state.UIStateKey)
• Show version (--version)
• Show info (--info, like --version but also shows build date, commit hash)
• Launch update without launching GUI (--update) (Depends on Self-update mechanism #32)
• Maybe hidden experimental settings could be toggled via CLI only
• Start with specific window dimensions (--width, --height)
• Maybe other stuff????