Overhaul PyBaMM solution importing

[tomjholland]

Importing PyBaMM solutions has some added complexity due to differences in standards between terminology for Cycles and Steps. In PyBaMM the last three instructions of the following experiment:

experiment = pybamm.Experiment(
        [
            (
                "Discharge at C/10 for 10 hours or until 3.3 V",
                "Rest for 1 hour",
                "Charge at 1 A until 4.1 V",
                "Hold at 4.1 V until 50 mA",
                "Rest for 1 hour",
            ),
        ]
        * 3
        + [
            "Discharge at 2A until 3.3 V",
            "Charge at 1 A until 4.1 V",
            "Discharge at 1A until 3.3 V",
        ],
    )

are separated by cycle number, not step number. They can be grouped into the same cycle, and thus increment step by putting them inside a tuple:

experiment = pybamm.Experiment(
        [
            (
                "Discharge at C/10 for 10 hours or until 3.3 V",
                "Rest for 1 hour",
                "Charge at 1 A until 4.1 V",
                "Hold at 4.1 V until 50 mA",
                "Rest for 1 hour",
            ),
        ]
        * 3
        + [
            ("Discharge at 2A until 3.3 V",
            "Charge at 1 A until 4.1 V",
            "Discharge at 1A until 3.3 V",)
        ],
    )

In PyProBE, cycle only increments when steps are repeated. It should be ensured that the steps are properly separated, whatever the form of the experiment that created them.