Overlays Tweak

Males and females can have separate overlays now.

Default (used when gender specific overlay is not defined):
`overlay_worn_{ITEM_ID}`
`overlay_wielded_{ITEM_ID}`
`overlay_mutation_{MUTATION_ID}`

Specific for male:
`overlay_male_worn_{ITEM_ID}`
`overlay_male_wielded_{ITEM_ID}`
`overlay_male_mutation_{MUTATION_ID}`

Specific for female:
`overlay_female_worn_{ITEM_ID}`
`overlay_female_wielded_{ITEM_ID}`
`overlay_female_mutation_{MUTATION_ID}`

Both have combat knife, tank top and horns mutation
![gsoverlays](https://cloud.githubusercontent.com/assets/6969268/4419035/4fba012c-4566-11e4-8a06-54a0114e18ff.png)