Automatically generate screenshots for all examples (#2379)

sh/generate_example_screenshots.sh

@@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+# This script generates screenshots for all the examples in examples/
+
+set -eu
+script_path=$( cd "$(dirname "${BASH_SOURCE[0]}")" ; pwd -P )
+cd "$script_path/.."
+
+cd examples
+for VARIABLE in $(ls -1d */ | sed 's/\/$//'); do
+    EFRAME_SCREENSHOT_TO="$VARIABLE/screenshot.png" cargo run -p $VARIABLE
+done