Add a script for pip installing the packages in dev mode

packages/package-dev-install.sh

@@ -0,0 +1,20 @@
+#!/bin/bash
+#
+# Install packages in development mode, for running installed Galaxy from the source
+#
+set -euo pipefail
+
+up_to="${1:-}"
+
+if [ -n "$up_to" -a ! -d "$up_to" ]; then
+    echo "ERROR: package does not exist: $up_to"
+    exit 1
+fi
+
+while read package; do
+    [ -n "$package" ] || continue
+    pushd $package
+    pip install -e .
+    popd
+    [ "$package" != "$up_to" ] || exit
+done < packages_by_dep_dag.txt