Force Quick Look to treat .in files like .txt files
Install QLStephen:

wget https://github.com/downloads/whomwah/qlstephen/QLStephen.qlgenerator.zip
unzip QLStephen.qlgenerator.zip
mkdir -p ~/Library/QuickLook
mv QLStephen.qlgenerator ~/Library/QuickLook
qlmanage -r