Fixed: building on 10.6 failed.

There are features of Objective-C 2.0 used in XcodeCapp that cannot be compiled with Xcode 4.2, which is the maximum version that runs on OS X 10.6. Users on 10.6 would see compile errors.

Now a check for OS X 10.7+ is done, and on any version earlier than that, the user is presented with a message telling them to download XcodeCapp from the web site.

Tools/XcodeCapp/XcodeCapp.xcodeproj/project.pbxproj

@@ -391,7 +391,7 @@
 			isa = XCBuildConfiguration;
 			baseConfigurationReference = E164FDEF1720E7FA00263CE3 /* Debug.xcconfig */;
 			buildSettings = {
-				DSTROOT = "$(HOME)";
+				DSTROOT = /;
 			};
 			name = Debug;
 		};
@@ -401,7 +401,7 @@
 			buildSettings = {
 				COPY_PHASE_STRIP = NO;
 				DEPLOYMENT_LOCATION = YES;
-				DSTROOT = "$(HOME)";
+				DSTROOT = /;
 			};
 			name = Release;
 		};