feat: Make sure build-essential is installed

- The Python modules installed by initenv.sh require a compiler to build.
- Revised initenv.sh to check whether build-essential is installed
  before proceeding, if the system is based on Debian or Ubuntu.

Author: cliffmccarthy

scripts/initenv.sh

@@ -9,6 +9,11 @@ if command -v lsb_release 2>&1 >/dev/null; then
         echo "You need to install python3-dev for installing the other dependencies."
         exit 1
       fi
+      if ! dpkg -l | grep build-essential 2>&1 >/dev/null
+      then
+        echo "You need to install build-essential for building Python dependencies."
+        exit 1
+      fi
       ;;
   esac
 fi