Changed get_project_dir to be more consistent / intuitive

[bmingles]

I updated the logic in get_project_dir to be more predictable.

• Projects now search in workspace folder order to ensure multi-root workspaces select first project instead of shortest path
• File tree depth is now considered as part of checking "top-most" / "best" file within a particular workspace. This ensures that project files at same depth use the first project and not one with shortest parent folder path

resolves #921