Provide coercing methods for the jailed configuration: getintXXX(), getboolXXX(), getfloatXXX() and friends. This is done be refactoring Configuration and putting the coercing methods into a common mixin.

# -*- 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
key6 = "off"