Improvement of ep.pp.qc_lab_measurements

[xinyuejohn]

Description of feature

There are two things could be improved for qc_lab_measurements

1. Adding more reference table.
   Currently there are only Clinical Laboratory reference values. Other reference values (like clinical measurements of vital signs) may also be very helpful.
   -> Easy to do, but need to do some research
2. better fuzzy matching
   Currently this function may give incorrect matchings. It would be great that it can print similar matches if the matching is not exactly same.
   -> Also easy to improve. There's already a very similar function in ehrdata

[xinyuejohn]

I will improve this issue later because I will test the function with the ehr data I have