dev: add import_assets.sh

dev/HOW_TO_IMPORT_ASSETS.md

@@ -1,12 +1,4 @@
 # How to import assets?
 1. `sudo apt install magickimage`
-2. cd to a directory where there is *only* .png files (or subdirectories)
+2. cd to a directory where there is .png files
-3. Execute
+3. Execute `dev/import_assets.sh`
-```sh
-for PNG in $(find . -type f -name "*.png")
-do
-	convert "$PNG" -alpha opaque "${PNG%.png}.xpm"
-	convert "$PNG" -alpha extract "${PNG%.png}.alpha.xpm"
-	rm "$PNG"
-done
-```

dev/import_assets.sh

@@ -0,0 +1,7 @@
+#!/bin/sh
+for PNG in $(find . -type f -name "*.png")
+do
+	convert "$PNG" -alpha opaque "${PNG%.png}.xpm"
+	convert "$PNG" -alpha extract "${PNG%.png}.alpha.xpm"
+	rm "$PNG"
+done