-preview=safer for D

[Walter Bright]

Safer offers no guarantees of memory safety. I view it as a tool to:

1. provide some lint-like flagging of suspicious constructs

2. help educate new D users to safer practices

3. make it easier to transition to using @safe

You are an expert, and I doubt it will be of much value to you as you are 
already an expert in what is safe and what isn't.

Memory safety, as I predicted a few years back, is now a critical feature of a 
programming language, and whatever practical way we can move D in that direction 
we must do.