Replace File.cpp and Directory.cpp with Boost Filesystem

[Robert Massaioli]

Boost Filesystem should be able to do a great many things that those classes can do. Use it to replace them.

[Robert Massaioli]

The first working version of this can be found on the boost_filesystem branch at commit: c113549f3e874478721822be1f1d9b37be58b510

However this is not done yet and there is still more work left to be done.

[Robert Massaioli]

This is related to issue #9

[Robert Massaioli]

This issue is now done and it works well. I have tested it with a few different directory structures and it seems to do exactly what I expect.