This MR makes Builder finalizable into vectorized systems. Extra option is introduced:
syst = builder.finalize(vectorize=vectorize)
vectorize can be
False is the legacy and default behaviour. The difference between two latter is that
vectorize=True assumes that value functions are already in vectorized format (accepting site array pairs) and
vectorize="vectorize_values" assumes that value functions are in old format and converts them into vectorized format using an unoptimized Python loop.
Depends on !386 (closed)