enhancements to external menu mod

• gamemenu functionality
• add commands to any menu item
• built-in commands for common functions (feedback, etc.)
• use mod for displaying section menus (toggled with modopts)
• better input handling
• use require instead of load (more efficient)
• fix tabs in source
• fix bug with multicolumn display

changed the description

approved this merge request

merged

mentioned in commit 39ffd8cf