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_resize.sh

@@ -10,6 +10,8 @@ if [ $# -eq 0 ]; then
     exit 1
 fi
 
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+
 echo "Resizing large JPGs in ZIPs"
 
 # Use RAM disk for temporary files.
@@ -64,7 +66,6 @@ for INFILE in "$@"; do
         cleanup_temp
         continue
     fi
-    SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
     "$SCRIPT_DIR/images_resize.sh"
     popd > /dev/null
 
@@ -88,7 +89,7 @@ for INFILE in "$@"; do
     if [ ! -s "$OUTFILE" ]; then
         echo "Error: Output file is empty or does not exist. Keeping original file."
         cleanup_temp
-        exit 1
+        continue
     fi
 
     rm "$INFILE"