fix get_child , avoid one extra query in node construction
Add 2 tests
add test , creating two time the same node MUST raise exception
remove print
adapt to changes from treww
return array variant as python list even when size is one, rename From* methods to To*. It is much clearer
fix array test. Add test for get_child with deep path
Merge pull request #4 from oroulet/master

fix variant array handling, add more tests