Increased effect range of Tactical Overseer effect from 55 to 65
Executor stats altered:
-10 armour, -3 MA, -2 weapon damage, -3 MD, +2 health per model

Executors have +1 health per model and have a new AI usage type, so they shouldn't enter melee with them.

Added the custom units to the allied recruitment table

Improved the Nan-Gau Archer unit card slightly