point behavior on different compilers.  In particular, this change avoids having
false "impossible truth box" exceptions being thrown when the object detection
tools are used with the mingw gcc compiler.

prevented the load_image_dataset() routine from working on Windows systems in some
cases.

when they reference each other.

instead of compiling the all/source.cpp file since this results in smaller
binaries in many cases and also sometimes improves compilation speed.

individual .cpp files instead of the single large all/source.cpp file.

incorrect results.