pipline based definition for inputs

[zhubonan]

Setting builder for AiiDA input can be interactive but can be very expliticy. At the moment, pre-defined default inputs for VASP can be prepared using VASPInputset but the user still have to link it up to each input port.

An alternative approach is to define the input as a pipline, encourages code resuse.
So a workflow can be defined as:

pipeline = BuilderPipline(process_class).default().override_incar(...).set_computer(...)
pipeline.set_resources(...)

def use_pbesol(pipeline):
    pipeline = pipeline.override_incar(...).set_pseudos_family(...)
    return pipeline 

def use_myriad(pipeline):
    pipeline = pipeline.set_resources(...).set_code(...)
    return pipeline 

pipeline = input_for_relax(pipeline)
submit(pipline.builder)