Instead of relying on magic in setFocus(TabFocusReason) use selectAll()

Task-number: QTCREATORBUG-369

Rename arguments to allArguments(), qmakeArguments() to userArguments()

Fix for that will come later

instead of a Project. Since BuildSteps "should" only care about the
BuildConfiguration not the Project. (Not 100% doable, but still.)

Note: I didn't fix all the connects and there are a few missing things.
This compiles, more work is coming.

The pointers can be used to distinguish BuildConfigurations

The project() should in most cases not matter, instead the
BuildConfiguration should. This shows all the information that needs to
move into the BuildConfiguration classes.

More API work.

Each project has it's own BuildConfiguarion * classes, they'll get a
decent type safe interface and the setValue/value stuff will be removed.

1. allow empty overlay selections
2. make it possible to bind a selection to a specified length

 * Fix reordering of build steps in the clean list of steps.
 * Make the code more robust and avoid removing and inserting
   the item.
 * Update code for the build steps list too for reasons of symetry.

Reviewed-by: dt