Revert "Revert "Uses a better cleaning command, closes #2203""

This reverts commit f2742b8.

That's not the JS breaker

Author: zoffixznet

util/update-and-sync

@@ -30,7 +30,10 @@ echo 'Cleaning out old HTML files'
 # don't clean out html/ entirely, because there are some files
 # under version control there
 # build-log has been moved elsewhere, however
-find html/ -name '*.html' -delete
+# find html/ -name '*.html' -delete # This was the former order
+# This new one will clean all files not under source control.
+# Use only in the machine where you are going to run things.
+git clean -fd
 
 # if the htmlify fails, sync the build log.
 # since sync-build-log returns false, not the whole thing is synced