allow BSE::ComposeMail to accept variables
audit log mailing now uses the most specific email address supplied

eg.

[mail audit log]
error=abc@example.com
bse-component-module-function=1
bse-component-module=def@example.com

will use def@example.com when mailing an audit log message of the
appropriate type.
define variables for audit log mails and re-organize

also added an object() method to entries
add a set_subject() function to BSE::ComposeMail templates
add a bse.debug() function that writes it's arguments to stderr
add substring() and match() methods to scalars
add a new .while construct to templates
crazy subject handling for the audit log email template