Implemented the "ref" namespace to get configuration tree references. BUGS: - Tests should be done more thoroughly and extensively - Interaction of tree references and variable substitution should be tested more properly - Documentation is missing yet

# -*- coding: utf-8; -*-

__comment1 = "Comment 1"
key1 = "the value"
key2 = 2
key3 = 5.7
key4 = true
key5 = false
key6 = 0o377
__comment2 = "Comment no 2"
key7 = "Umlaute: ÄÖÜäöüß"