Add dev container configuration (#23)

* add devcontainer support files
* update rbuild to look in /usr/bin/openscad-nightly for openscad-nightly

.devcontainer/devcontainer.json

@@ -0,0 +1,19 @@
+// For format details, see https://aka.ms/devcontainer.json. For config options, see the
+// README at: https://github.com/devcontainers/templates/tree/main/src/debian
+{
+	"build": { "dockerfile": "dockerfile" },
+	"features": {
+		"ghcr.io/devcontainers/features/python:1": {
+			"installTools": true,
+			"version": "latest"
+		}
+	},
+
+	"customizations": {
+	},
+
+	"remoteUser": "vscode",
+	"mounts": [
+      "source=rackstack-bashhistory,target=/commandhistory,type=volume"
+  ]
+}