Add new Circuit, Gate, Lane, Moment types

[mofeing]

while thinking about adding new features around connectivty between Quantums, Ansatz and so, i needed to add this functionality to better represent quantum circuits or TEBD decompositions.

@jofrevalles this should fix your problem with getting the gates from a circuit in order. the only thing left to do for you to work is to implement a graph traversing o graph walk algorithm on top of Circuit.

notes

• Gate is nice. it's a Tensor with Site information, just like Quantum is a TensorNetwork with Site information.
• Lane and Bond are going to be used for helping Ansatz. i need them for the PEPS.
• Moment can also be used for stacking Quantums in a new type i'm designing for representing compositions of TNs.

to do

we probably need to change the name of Moment because it means other thing in quantum circuit libraries

[mofeing]

in the end, this PR got bigger than what i wanted but everything in here was needed

there is really no breaking changes, except for...

• Lattice (and thus Ansatz) now uses Lanes and not Site
  • this fixes issues with canonization on Operators like MPO or dual states
  • also it's better defined
• tensors(; at), tensors(; bond), tensors(; between) now requires you passing a Lane
  • inds(; at) still accepts Site
• simple_update! now only accepts Gate, and not a "not very-well defined" Quantum

i want these breaking changes to be before 0.8.0 so expect another PR where i better define Ansatz with mapping between Lane to Tensor and Bond to index.

@jofrevalles i'm merging directly because i'm lil bit on a hurry and need this to implement PEPS. this stuff is still not very documented because i don't want it to be public yet: it will be public after some features that can be added on v0.8.x, but meanwhile you can start using Gate and Circuit for your work

tests pass... it's just the Reactant problem right now