Eclectic set of changes.

- Added the *list* method to directory (somehow this was never added). Gave it access to the "consistency" and "quorum" operational parameters.
- Added *create*, *delete*, and *pop* methods to the *inorder* module.
- The *list* method in the *inorder* module now longer defaults *sorted* to *False*.
- Added *consistent*- and *quorum*-related parameters to value-node *get* method.
- Added *atomic_update* method to *node* module. This repeatedly invokes a callback with the current value of the given path until it can successfully set it atomically.