Add templete for new method

[ohno]

Minimal:

struct NewMethod
  # settings
end

struct ResultNewMethod
  # settings
end

function solve(hamiltonian::Hamiltonian, method::NewMethod)
  # calculation
  return ResultNewMethod()
end

function expectation(result::ResultNewMetho, o::Operator)
  # calculation
end

Optional:

Base.show(io::IO, method::FiniteDifferenceMethod) = print(io, Base.string(method))

Base.show(io::IO, result::FiniteDifferenceMethodResult) = print(io, Base.string(result))

Base.string(method::FiniteDifferenceMethod) = "FiniteDifferenceMethod(" * join(["$(symbol)=$(getproperty(method,symbol))" for symbol in fieldnames(typeof(method))], ", ") * ")"

function Base.string(result::FiniteDifferenceMethodResult)
  # ...
end

function verification(result::FiniteDifferenceMethodResult)
  # ...
end

[ohno]

Add to documentation or sorce code.