Validates the scar against the soldier type, mainly an issue because Skirmishers have scars only for them.

Fixed (hopefully!)...

Doesn't crash on disabling anymore.
For savegames from before this update, changes will take effect from the next time you go on a mission.
(in mission saves never crashed on removing the mod)

FIxed up gravely wounded scarring, now should work properly when enabled mid compaign or if an old scar is removed.
Tidied up mod so all code now in one class.