Turn output of -vtemplates into compiler-messages and show template instances

[jmh530]

On Thursday, 3 September 2020 at 13:13:40 UTC, Per Nordlöw wrote:
> D just got a better formatting of existing template usage 
> sorted by descending unique instantiation count via the flag 
> `-vtemplates`. Each template that has a least one instantiation 
> is now printed using standard compiler diagnostics formatting 
> for easy navigation to the point of its declaration.
>
> [snip]

Nice.

People also might find it useful to filter for just one template 
(and show all the instances).