nested_set_options accept both Class & AR Relation.
Test nested_set_options with class & relation arguments
Merge branch 'master' into relation
Merge branch 'master' into relation
Split on two lines for better readability
add method move_to_child_with_index
Merge pull request #126 from BenZhang/master

add method move_to_child_with_index
Now when a record has not yet been created but a parent_id is assigned we can still detect what the root will be.
Added test for updating the depth of child nodes when a parent node is moved. [#120]
Naive solution for #120 (updating depth of child nodes when parent node moved).
Merge pull request #129 from awagener/update_child_depth

Update child depth when parent node is moved
.root should be self when the current node *is* the root.
Check an interface instead of a class.
Documented changes since 2.1.1
This is version 2.1.3
- Added tests for moving nodes from 1 scoped tree to another
Reduce the number of queries triggered by the canonical usage of `i.level` in the `nested_set` helpers.
Merge pull request #123 from semaperepelitsa/relation

make nested_set_options accept a relation in addition to a class
Merge pull request #135 from thedarkone/levels

nested_set helpers and #level query counts
Merge pull request #131 from igagnidz/master

Regarding issue #130