[mod] update to new simplified path
[mod] add root() to get root holder node
[mod] add bounding box helpers
[mod] add function to get node by (line, column)
[mod] get bounding box of a node's attribute
[fix] from_baron_path when value is a builtin

The check on string_instance was not enough because the value of a Node
can be an int for example. If that's the case, from_baron_path went
1 child too far and did not return a Node or NodeList but an int.
Now, from_baron_path stops at the last redbaron node.
[mod] make root a property
[mod] make bounding_box a property
[mod] give directly line and column
[doc] doc for bounding_box
[doc] doc for find_by_position
[mod] use simplier writing for isinstance
[mod] test bounding_box on empty NodeList
[fix] missing method names in not_helpers
sync with master branch
[fix] use new root property
[mod] absolute_bounding_box becomes a property

To get the attribute, you must now call
get_absolute_bounding_box_of_attribute()
[doc] update doc for new property
Merge remote-tracking branch 'origin/bounding_box'

Conflicts:
	redbaron.py