Derma_StringRequest children access from obj

[BullyHunter32]

made the children accessible from the returned object, used this for the AllowInput on the text entry, twas pretty handy.

[WilliamVenner]

Have needed this many times before, with the exact same use case :v

[robotboy655]

Probably should only do this for the text entry itself, not for everything, or have AllowInput be a callback argument.