Expose getPath

[hasufell]

While working on haskell/filepath#250 I realized I need to inline insane amounts of code. Then I found out that directory basically already has what we need in internal modules. My understanding is that this would fit well in directory API, since it also deals with XDG. So PATH doesn't seem to be far fetched.

This would also allow me to deprecate the problematic getSearchPath in filepath.

[hasufell]

As a sidenote: the identifier is named getPath as to not clash with System.FilePath.getSearchPath since they're often imported together

[Rufflewind]

I will probably rename this to something more specific like getExecSearchPath to avoid confusion and possible conflicts with user-defined functions.

[hasufell]

I will probably rename this to something more specific like getExecSearchPath to avoid confusion and possible conflicts with user-defined functions.

Makes sense.

[Rufflewind]

Thanks for the PR!