`with (TemplateInstance):` shoild work

[Andrei Alexandrescu]

I just tried this:

template x() {
     void fun(int) {}
}

void main() {
     with (x!()) {
	    42.fun();
     }
}

It works, and it's a great way to inject UFCS symbols. But at best it 
should work with the colon syntax so it applies through the end of 
scope/module:

with (x!()):

void main() {
     42.fun();
}

Once that is possible, you get to inject UFCS symbols into a module with 
ease.