* Travis: speed up by caching base and running luacheck earlier
* ignore bin and install for git status change detection
* skip coverage except on official master branch. It adds 3 whole minutes and does nothing to prevent regressions
* also cache ~/.luarocks. It evens out but would generally prevent remote timeout shenenigans
* remove base cache dir before caching with verbose remove to see what's going on
* more inclusive shell code quality analysis
* fixed more shellcheck issues
* better shellcheck/shfmt debugging info