beforeAttachmentSaveHandler(\%attrHash, $topic, $web )
\%attrHash - reference to hash of attachment attribute values
$topic - the name of the topic in the current CGI query
$web - the name of the web in the current CGI query
This handler is called once when an attachment is uploaded. When this
handler is called, the attachment has not
been recorded in the database.
The attributes hash will include at least the following attributes:
attachment => the attachment name
comment - the comment
user - the user's TWiki user object
tmpFilename - name of a temporary file containing the attachment data
TWiki::Plugins::VERSION = '1.023'