check recipes in travis, fix or muffle warnings

suppressed warnings: -Wno-features -Wno-github -Wno-autoloads, because
too many recipes trigger them to handle right now.
check-recipe-batch: recipes/*.rcp -> recipes/

The travis script has set -e enabled which prints out command line to be
executed. However, it prints the command line after glob expansion, so
having recipes/*.rcp in a command would be a pain to scroll through.