Full directory scan

[rogermartensson]

Not sure if this can be done.

I would like to be able to do a full directory scan (or workspace) to be able to see all the problems in the PROBLEMS tab without needing to open up every file in the editor.

This is of course an expensive action so I think this is best implemented as a Command that a user can invoke if need.

This I guess would need some visual feedback. Like issue #66.