v0.3.9

Changed

• tetragono: The interface of save_result allow only (state, result, whole_result) now.
• TAT.hpp: Change the view of sign problem in conjugate, there is only one conjugate, but the trivial metric may not
  be positive definite, so in gradient descent, this negative metric term need to be considered, the optional paramter
  trivial_metric is used to apply the trivial metric when conjugating.
• TAT.py: Update the new interface of conjugate.
• TAT.py: Use customized string stream in TAT.py to avoid a duplicated copy of string.
• TAT.hpp: Check the larger tensor to try to fit the common edges in contract, if not proper, check the other one. The
  previous behavior always check tensor 1 firstly and check tensor 2 secondly.
• scalapack.py: Change the loader API. The previous way is from PyScalapack import Scalapack and using
  Scalapack("libscalapack.so") to get the scalapack object, Now user should use import PyScalapack and
  PyScalapack("libscalapack.so") directly.

Removed

• TAT.hpp: Remove deprecated tensor member function get_rank, find_rank_from_name and get_rank_from_name.

Fixed

• TAT.hpp: Fix a bug about parity sign when merge_map is empty.
• TAT.hpp: Fix invalid access to a empty vector when splitting the first edge into zero edges.
• TAT.hpp: Fix out of range pointer error when try to split a trivial edge {{Symmetry(), 1}} to no edge, or merge no
  edge into a trivial edge.
• TAT.hpp: Fix an out of range bug in identity.hpp. It created a pod vector with memory reserved and use the item
  directly previously, without resize, which would not cause critical issue in fact. Emplace the item when using now.