Customized KPI Calculation

[dhblum]

This issue is to integrate the customized KPI calculation.

To Do:

• Merge from Sen's development
• More documentation in docstrings and readme.
• Delineate required and optional keys in kpi config.
• Make data_point_num not required for be specified for all kpis.

[SenHuang19]

I accidentally commit to the issue83_customKPI branch directly

[dhblum]

No problem, this works too!

[dhblum]

I've merged the most recent master to the branch.

[dhblum]

Hey @SenHuang19 , here are comments I have:

• More documentation could be added, particularly as docstrings for method and class descriptions and a guide (in the form of a readme) for potential users who want to adopt the capability as you demonstrated.
• It seems that the kpi configuration file has a number of keys that are required, and some that are not. I suggest somehow delineating between which are required and which are not.
• I don't think data_point_num needs to be in all KPI configuration files, but instead could be handled within the KPI calculation classes themselves, since they are classes and have memory. Removing this from the config or making it optional simplifies the interface I think.

I've added a suggested to-do at the top comment.

[SenHuang19]

Update the pull request #95
Specifically, I made the customized KPI compatible with both testcase 1 and 2

[dhblum]

I merged #95 and opened #143 for merge to master.

[dhblum]

Closed by #143.