(GH-508)(GH-509) shimgen fix/improvements

 - Shimgen no longer changes the working directory to target files (this only
   occurred for GUI apps)
 - Adding --shimgen-log to the end of a shim call command will cause the shim
   to log to the console information about what it is doing
 - Adding --shimgen-usetargetworkingdirectory to the end of a shim call will
   cause it to use the target executable's working directory instead of the
   current work directory.