Added iteration ordering attribute to the Mesh class and a method to return ve_idx in any iteration order.
Cleanup for PR.
Added default argument to structured_iterate_ve_idx.
Added Parameters to Mesh __init__(), removed Parameters from Attributes.
Added iteration ordering attribute to the Mesh class and a method to return ve_idx in any iteration order.
Cleanup for PR.
Added default argument to structured_iterate_ve_idx.
Added Parameters to Mesh __init__(), removed Parameters from Attributes.
Rebased against #276 and updated accordingly.
Fixed merge conflicts
Minor cleanup.
Merge branch 'struct_iter' of https://github.com/elliottbiondo/pyne into elliottbiondo-struct_iter