ATGC_NO_INPUT=false switched non-interactive mode on while ATGC_USE_BOBBIN=false switched the index off; the log paths took `off` and nothing else. One reading now lives in src/env.rs and all of them go through it, so unset, empty, 0, false, no and off are off and anything else is on. CI is read the same way; NO_COLOR keeps its own spec. Change-Id: Ib733dcca81ddaabf08bdc230f4ecb384141d2601