Add coverage highlighting to IDE

[alex]

On Saturday, 23 March 2013 at 23:14:59 UTC, Walter Bright wrote:
> Just an idea for an IDE.
>
> At the push of a button, run the unittests with -cov on the 
> module being editted, read the coverage listing file, and then 
> highlight the code lines that were never executed.

How to run only one module('s unittests)? With rdmd? Or just via 
dmd with a specific flag set?