This is needed by - for example - WordPress because it allows for
different permalinks schemes.
For example, /foo could be a permalink that should be directed to
PHP, while /favicon.ico is a file that must be served statically.
URI /foo would be matched by the default servlet resulting in a 404.
Therefore we need a filter mapped to /* that checks whether the
request URI is a file that exists and likely to be served by the
default servlet, otherwise it needs to rewrite the URL to something
like /index.php?p=/foo.
The rewrite filter does not have the functionality of "try the file,
if missing then rewrite" that is now implemented by the TryFilesFilter.
Simone Bordet