Order

dataset = order.Dataset("ttbar", 1, processes=[process])

or shorter:
dataset = prder.Dataset("ttbar", 1, processes=[
dict(name="ttbar", id=1, xsecs={13: 831.76})
])

- Add 'gen_order' attribute to Dataset. (9d82d6c)

- Allow arbitrary xsec keys in process. (c70e877)
- Don't overwrite by default in UniqueObjectIndex.extend. (b4d8d75)
- Add tree search algo aliases for walking. (7870233)
- Fix pretty printing of processes. (30c5fcf)
- Improve doc strings. (aaf020f)

- Refactor unique object tree walking. (4340a6f)
- Update legacy tests. (ee3215a)
- Do not accept None as shift name. (fb0ee7d)
- Streamline existing API docs. (2b2b695, 3671a13)

Features & updates

- Rename selection_mode to str_selection_mode. (934e065)
- Modernize docs (523dd78, dbbde2a, 89b790e)


Fixes

- Remove duplicates in get_{leaf,root}_ tree methods. (2af864b)
- Fix category copy_shallow (cda3833)

Features

- Add copy_shallow to all objects. (376f08f)
- - Add discrete_{x,y} flags to variables. (2b97da5)
- Refactor docs. (343210c)

Fixes

- Fix variable get_full_y_title. (31dcbc1)

Breaking changes

- Rename log_{x,y} and discrete_{x,y} attributes of Variable. (ead2d20)