xctool and Travis-CI test configuration

• `.xctool-args`, with all the workspace/scheme/configuration/sdk/arch settings needed for xctool to run a full test with just `xctool test`
• `.travis.yml`, with added before_install and script declarations to install xctool and run it, respectively
• `P-001.G-imr.xcscheme`, now a “shared” scheme (rather than just a per-user scheme, I guess) so that Travis-CI has a scheme to uh dig.  Or wire up. … _I'm honestly not sure what profession Mr. Travis belongs to._