- Added functionality to compute the graph structure directly inside :class:`~tenpy.networks.mpo.MPO` and determine the upper triangular ordering for an infinite MPO.
- Implemented the scheme from [Phien2012] inside :class:`~tenpy.networks.mpo.MPOEnvironmentBuilder` for iterative computation of `init_LP`/`init_RP`. Works also for higher powers of extensive MPOs.
