[QBS] QBS default build directory

[Jake Thomas Petroules]

I had an idea for QBS that I think would be rather convenient. Currently, when you run a build, a directory for the profile is created in the current directory with the name of the profile. It would be nice if (by default), the build directories were named `qbs-build/<profile>` rather than simply `<profile>`. If you have multiple profiles set up, it's much easier to ignore a single directory that's always named the same, rather than a bunch of directories that may be named differently for each developer's setup.

I know that you can just `mkdir qbs-build && qbs -f ..` but I think that placing profile build directories within a `qbs-build` directory by default would be a cleaner and more convenient approach. Helps avoid name collisions, too. Thoughts?

Jake Petroules
Petroules Corporation (www.petroules.com)
Email: jake.petroules at petroules.com
Telephone: +1 (970) 587-3821