Vidjil: Two JsonList objects were not deleted.

Fixed thanks to Valgrind.
tests: stanford-germlines.should_get, testing '-c germlines'
vidjil.cpp, -c germlines: correctly computes stats_max
vidjil.cpp, -c germlines: display total number of kmers
tests: vidjil-help.should_get, testing help and default options
tests: vidjil-warning-*.should_get, test warnings on non-optimal use