fix illegal chars in title

scrape.sh

@@ -94,7 +94,15 @@ scrape_book() {
       fi
       scrape_book_chapter "$chapter" > "$f"
       log scraping book title from $f
-      local title="$(grep '^\#' "$f" | head -n 1 | sed 's/^\#*//' | sed 's/^[ ]*//' | sed 's/[ ]*$//')"
+      local title="$(
+         grep '^\#' "$f" \
+         | head -n 1 \
+         | sed 's/^\#*//' \
+         | sed 's/^[ ]*//' \
+         | sed 's/[ ]*$//' \
+         | sed 's/[ ][ ]*/ /g' \
+         | sed 's/[^a-zA-Z0-9]/_/g' \
+      )"
       if [ -z "$title" ]; then
          title="${chapter%/}"
          title="${title##*/}"