Simplification of @trusted

[RazvanN]

Currently, @trusted applies only to functions. This is most of 
the times a pain when you want trusted code blocks inside 
functions. Why not simplify it a bit by using trusted scope 
blocks? E.g. this:

```d
void foo() @safe
{
     () @trusted { ... }();
}
```

becomes this:

```d
void foo() @safe
{
     @trusted
     {
        ....
     }
}
```
To make things easier, @trusted does not insert a scope (similar 
to `static if`).

Of course, the feature would be additive (you can have both 
trusted functions and code blocks).

That would also provide an elegant workaround if void 
initialization is rejected in @safe code [1][2]. For example:

```d
void foo() @safe
{
     @trusted
     {
         int[100] a = void;
     }
     ...
}
```

What do you think?

Cheers,
RazvanN

[1] https://issues.dlang.org/show_bug.cgi?id=17566
[2] https://github.com/dlang/dlang.org/pull/2260