Make scripts generic and fix several bugs

- Add optional directory argument to images_resize_recursive.sh,
  zip_images_resize_recursive.sh, and new rar2zip_recursive.sh
- Remove hardcoded-path wrappers rar2zip_images.sh and rar2zip_incomplete.sh
- Fix zip_images_resize.sh: move SCRIPT_DIR to top, change exit 1 to
  continue on bad output file so remaining files still process
- Use MAX_PIXELS variable in images_resize.sh resize argument
- Fix zip_images_recursive.sh: replace case-sensitive 7z globs with
  find -iregex piped via xargs

zip_images_recursive.sh

@@ -20,11 +20,11 @@ if [ "$#" -ne 0 ]; then
     directoryTree="${1} - ${directoryTree}"
 fi
 
-jpgs=$(find . -maxdepth 1 -regextype posix-egrep -regex ".*\.(jpg|JPG|JPEG|jpeg)$")
+mapfile -d '' jpgs < <(find . -maxdepth 1 -regextype posix-egrep -iregex ".*\.(jpg|jpeg)$" -print0)
 
-if [ -n "$jpgs" ]; then
-   echo "Zipping JPGs in ${directoryTree}"
-   7z a -tzip -mx=0 "$directoryTree.zip" "*.jpg" -i!*.jpeg -i!*.JPG -i!*.JPEG
+if [ ${#jpgs[@]} -gt 0 ]; then
+    echo "Zipping JPGs in ${directoryTree}"
+    printf '%s\0' "${jpgs[@]}" | xargs -0 7z a -tzip -mx=0 "$directoryTree.zip"
 fi