DIP54 : revamp of Phobos tuple types

[ilya-stromberg]

On Monday, 23 December 2013 at 11:58:06 UTC, Dicebot wrote:
> Also having both types at the same time will cause difficulties 
> with template algorithms currently present in std.typetuple - 
> having some defined in terms of raw argument list and others in 
> terms of packed TemplateArgumentList is just another learning 
> curve damage.

OK, I convinced. It's definetly bad to have both `auto-expansion 
TypeTuple` and `TemplateArgumentList without auto-expansion` 
template algorithms.
So, I totally agree with this DIP, we need only 
`TemplateArgumentList without auto-expansion`.

BTW, I was very surprised when I saw the code from 
`std.typetuple.TypeTuple`:

alias TL = TypeTuple!(int, double);

alias Types = TypeTuple!(TL, char);
static assert(is(Types == TypeTuple!(int, double, char)));

It's definitely better to have `.expand` property:

alias Types = TypeTuple!(TL.expand, char);