syntax sugar: std.path::buildPath instead of from!"std.path".buildPath

[Timothee Cour via Digitalmars-d]

> Doesn't add indentation:
>
> with (module_!"std.stdio, std.traits")
> void fun(T)(File input, T value)
> if (isIntegral!T);

* what is the implementation of `module_` ? `from` defined earlier
doesn't allow for multiple modules as in from!"std.stdio,
std.traits"`. But let's assume it can be done for now.

* when `with` covers multiple declarations, it adds indentation:
with(module_!"std.stdio"){
  declaration1;
  declaration2;
}

* when `with` covers a single one, it doesn't add indentation, but
then `::` can be used instead, with arguably simpler syntax:

`void fun(T)(std.stdio::File input, T value);`
vs
`with (module_!"std.stdio") void fun(T)(File input, T value);`


> with/module_ solves the UFCS member stand-in problem elegantly, how does your proposal solve it?:
> with (module_!"std.range.primitives")
> void func(alias pred, R)(R range)
> if (isInputRange!R && is(typeof(pred(range.front)) == bool);
>
> .front has to refer to *either* a member or an imported UFCS function.

UFCS equally affects the `::`  proposal and the
`module_!""`-without-`with` proposal.

Besides the option of not using UFCS, we can actually use Alias for
this, as I've proposed a while ago in
http://forum.dlang.org/post/mailman.1002.1370829729.13711.digitalmars-d-learn@puremagic.com:

`with (module_!"std.range.primitives") ... pred(range.front)`
vs:
`... pred(range.Alias!(std.range.primitives::front))`

or, if a feature that I've proposed earlier in
http://forum.dlang.org/post/mailman.1453.1369099708.4724.digitalmars-d@puremagic.com
(support UFCS with fully qualified function names) is accepted, it
becomes even simpler:

`... pred(range.(std.range.primitives::front))`


To reiterate what I said earlier:

* `foo.bar::symol` is very well suited for the common case of 1-off
imports, ie when the import is only needed at a particular location.
This is a common case.

* If we want to cover multiple declarations, using something like
`with (module_!"std.stdio, std.traits")` makes sense and is more DRY.