Shorten the generated test file names.

Also place the generated files in their own directories.

Change-Id: I51c1acf15810ec199d17cc2d6e63adebdc0fc3c9
diff --git a/api/Utilities.h b/api/Utilities.h
index 8b0cd9c..04169dc 100644
--- a/api/Utilities.h
+++ b/api/Utilities.h
@@ -57,7 +57,7 @@
 
 public:
     // Opens the stream.  Reports an error if it can't.
-    bool start(const std::string& name);
+    bool start(const std::string& directory, const std::string& name);
 
     // Write copyright notice & auto-generated warning in Java/C style comments.
     void writeNotices();