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 -*-

key1 = "in the root namespace"
key2 = "in the root namespace -- too"

[tree1]
key3 = 0x20

[tree1.tree2]
key4 = "get this as `tree1.tree2.key4'"
key5 = true