Merge pull request #4515 from brianloveswords/safer-install-script

Make install script safer

tools/install.sh

+function main() {
 # Use colors, but only if connected to a terminal, and that terminal
 # supports them.
 tput=$(which tput)
@@ -117,3 +118,6 @@ echo 'p.p.s. Get stickers and t-shirts at http://shop.planetargon.com.'
 echo ''
 printf "${NORMAL}"
 env zsh
+}
+
+main