Add breakpoint conditions

[Rainer Schuetze]

On 24.09.2017 01:34, Joseph wrote:
> It would be nice if we could use the breakpoint conditions like only 
> breaking after hit N times. The error message as D does not support 
> them, but I'm sure it can! With a little love, anything is possible!

This works with the mago Concord extension for the VS debugger, see 
http://rainers.github.io/visuald/visuald/Debugging.html#concord