Drugs with association to more than one gene were special cases for explanation

All drugs with multiple genes involved in resistance posed an issue when checking if mutations in the genes were known and existed in a susceptible isolate. Looping over each mutation in each gene did not work since it would add a susceptible isolate to both unexplained and explained if it had a mutation in a compensatory mutation and a causal mutation. This is fixed here with a list comprehension and the use of any(). The representation of these mutation in the unexplained-s file was also altered to display the mutations these susceptible isolates harbored.

Closes #29 (closed)