fix bug for sys_idx dependent trust level and add option for model_devi_job

[Cloudac7]

As mentioned in #746, there is a bug in #609 due to not converting str indexes to int ones. So the bug was fixed here. Also, the author of the issue mentioned that it would be more proper to select trust level for each iteration. So now, iteration dependent trust level for force and virial was supported. For example, just setting model_devi_f_trust_hi in model_devi_jobs:

"model_devi_jobs": [
    {
        "sys_idx": [0, 1], 
        "temps": [50,100],
        "press": [1.0,2.0],
        "trj_freq": 10,
        "nsteps": 1000,
        "ensemble": "npt",
        "model_devi_f_trust_hi": 0.30,
        "_idx": "00"
    }
]

However, it might be difficult to adapt different trust level for sys_idx selected in each iteration. So now, dict could be used to set the trust level in format like:

"model_devi_f_trust_hi": {
    "0": 0.160, 
    "1": 0.150
}

[Cloudac7]

Sorry, document change not pushed. Would be updated later.

[njzjz]

I don't quite understand here - why not directly use an integer?

[Cloudac7]

To make sure passing the original unit test. What only in need here is just to check whether the list and dict parser work and thus I made two examples. As a matter of fact, it should be refactored as normal usage, setting different values for each system.

[Cloudac7]

Well, it seems that the level does not affect the test result. I would change it to different values.

[njzjz]

I mean why {"1": 0.150, "0": 0.150} is not {1: 0.150, 0: 0.150}... I don't see the reason to use a str.

[Cloudac7]

Well, just in prevention of misleading, because most keys are string. Seems not to be so necessary.

[njzjz]

Oh you are right. JSON only allows string as the key... (Python does not)

[wanghan-iapcm]

Why not write it as

f_trust_lo = cur_job.get('model_devi_f_trust_lo', jdata['model_devi_f_trust_lo'])

[Cloudac7]

If written like this, on the condition that trust level only supplied in each model_devi_job, it might result in IndexError because of the lack of global trust level. It would be confusing for user to set global trust level when local ones set.