refactor helper function in own library

.config/yadm/bootstrap

@@ -6,24 +6,11 @@
 
 set -eu
 
-# Download file and return filename
-function download () {
-    [[ $# == 0 ]] && exit 1
-
-    local url="$1"
-    local suffix="${2:-"${url##*.}"}"
-    local filename="$(mktemp -t "download-XXXXXX.${suffix}")"
-
-    curl --location --output "${filename}" -# "${url}"
-
-    echo "${filename}"
-}
-
-export -f download
-
 # Directory to look for bootstrap executables in
 BOOTSTRAP_D="${BASH_SOURCE[0]}.d"
 
+export BOOTSTRAP_LIB="$BOOTSTRAP_D/lib"
+
 if [[ ! -d "$BOOTSTRAP_D" ]]; then
     echo "Error: bootstrap directory '$BOOTSTRAP_D' not found" >&2
     exit 1