add tests for loop_and_remove_seeds

[hbsmith]

to make sure the loop successfully removes compounds when using our sparse construction

[hayatehirai]

I leave a comment regarding the issue.
BioXP.jl line 400 would be:
(tT * X[end])[1] != sum_t && (x[i] = 1)
since (tT * X[end])[1] will return a Int64 value.