add basePath and other convencience path manipulation methods

[jesseeichar]

Email from Daniel Sobral:

I see "name" and I see "extension" on Path, but I don't see any way to
get the name *without* the extension. I'd expect to be able to get the
base directory, the base name, name plus extension, and directory plus
name plus extension. It seems there's a couple missing?

I think I will look at the jdk 7 Path to see what they have.