Make const, immutable, inout, and shared illegal as function attributes on the left-hand side of a function

[Martin Nowak via Digitalmars-d]

> This has been being brought up for years. I wouldn't expect 6 
> months to change
> anything. If we want to delay it until dmd's headergen and ddoc 
> are fixed and
> put a note in the changelog on the next release that it's going 
> to be
> deprecated rather than deprecating it immediately, we can do 
> that, but I don't
> think for a second that the arguments are going to change.

Automatic code rewriting is what might make syntax deprecations 
more feasible in 6 month.