disease.pvalue should be numeric

[KeithKelleher]

it's currently a varchar(255), but it seems like everything in there is a well formatted number, and could be numeric.
b/c sorting is weird as it is

[stevemathias]

This has been fixed in v6.7.0
It can be addressed in previous versions with the following:
mysql> ALTER TABLE disease MODIFY pvalue DECIMAL(20,19);
However, this results in one error:
ERROR 1292 (22007): Truncated incorrect DECIMAL value: '8.50137471674709e-70'
This can't be resolved as the maximum number of digits for DECIMAL is 65, so I just left it at 20.