Add isAbsolute field to path and treat relative/absolute/~ paths correctly in adaptors

[sverhoeven]

No description provided.

[atzeus]

This is fixed by the pull request #524

[sverhoeven]

The adaptors don't treat non-absolute paths themselves, they just pass them on their respective clients.

For example passing in a '.' to the file adaptor will return a listing of '/', instead of the expected listing of fs.getEntryPath().

In xenon-cli I now have to use:

public static Path getAbsolutePath(Path pathRelativeOrAbsolute, FileSystem fs) {
    if (pathRelativeOrAbsolute.isAbsolute()) {
        return pathRelativeOrAbsolute;
    } else {
        return fs.getEntryPath().resolve(pathRelativeOrAbsolute);
    }
}

I expected that adaptors would do this relative 2 absolute conversion for me.
I have added some tests to https://github.com/NLeSC/Xenon/tree/relative-file-tests branch that should pass adaptors did the conversion.

@jmaassen Should Xenon adaptors or the users of Xenon do this?

[jmaassen]

Fixed in 0b622b1

Added working directory and support for relative paths (resolved against this working directory) to all adaptors.