Fix Issue#104

[VinceNeede]

Added keyword tags to

function (::Type{MPST})(
  A::ITensor, sites; 
  leftinds=nothing, 
  orthocenter::Integer=length(sites), 
  tags::Vector{TagSet}=[defaultlinktags(i) for i in 1:(length(sites)-1)], 
  kwargs...
) where {MPST<:AbstractMPS}

Allowing to pass the tags to use in the factorization, using defaultlinktags by default.
Then changed the function

function setindex!(
  ψ::MPST,
  A::ITensor,
  r::UnitRange{Int};
  orthocenter::Integer=last(r),
  perm=nothing,
  kwargs...,
) where {MPST<:AbstractMPS}

To pass the correct linktags to the previous function. i.e.

  linktags=[defaultlinktags(i) for i in firstsite:(lastsite - 1)]

  ψA = MPST(A, sites; leftinds=lind, orthocenter=orthocenter - first(r) + 1, tags=linktags, kwargs...)

  ψ[firstsite:lastsite] = ψA

It can be tested that @assert hasdefaultlinktags(ψ) is valid