setter for value, iternext() and iterprev() to loop starting from
current element
richer iteration over nodes, with tests, docs and example
document and test that values become mutable
remove unnecessary node.value getter and setter
add dllist.insert(after=x), rename .nodes() to .iternodes()
new argument in nodes iterator: llist.iternodes(to=some_node)
new argument: node.iternext(to), node.iterprev(to)
fix changes desc
updated example
update changelog
Fix tested type
Fix typos in changelog and docs