Does what some people think ExtraSkillSlots does: adds an additional row of skills for vanilla characters, so you can use both skill variants.

• Engineer - not adding an extra slot for turrets.
• MUL-T - nothing is added.
• Captain - nothing is added.
• Bandit - not adding an extra slot for primary skill.

By default configs are configured to add skills only for vanilla characters (with exceptions listed above). You can enable extra skills for modded characters in corresponding config sections.