Add a SecureField

[yigitkerem]

Hey,

I needed to use a SecureField in my project for a password setting and thought the community might be interested too. Let me know if any adjustments are necessary. It works like this for me but please do your own testing too, I didn't delve to deep into the inner workings of the library and not everything may be good to go.

All the best & thanks for the awesome library!