Change field names to more intuitive ones

[peterk87]

e.g n_tiles_matching_positive_total to total_n_positive_tiles_expected

[mgopez]

Do you want me to do this with all fields containing *total?

[peterk87]

Yeah, I think so. We may need more guidance on what should be renamed to what, but I think it's okay to proceed with renaming whatever matches that pattern.

See Subtype class:
https://github.com/phac-nml/bio_hansel/blob/master/bio_hansel/subtype.py#L18

and SUBTYPE_SUMMARY_COLS global variable:
https://github.com/phac-nml/bio_hansel/blob/master/bio_hansel/subtyper.py#L20

SUBTYPE_SUMMARY_COLS is used to order the fields/columns in the DataFrame after Subtype instances are exported to dicts and merged into a DataFrame.

If you're using PyCharm, you can probably Shift+F6 to rename the fields/properties/variables.