Review Request: Allow to pass multiple targets and build variables to the make builder

[Alexandre Courbot]

> They do if you happen to set the same variable twice:
>  make X=abc X=def
> will produce different results than
>  make X=def X=abc
> That might be poor style, but it would be surprising to type it in this
> order just to find out that Kdevelop reorders it in a way that you can't
> change.

Point taken - I will replace the QMap by something that preserves order then.

Alex.