Implementation for: http://issues.roundup-tracker.org/issue2550731 Add mechanism for the detectors to be able to tell the source of the data changes. Support for tx_Source property on database handle. Can be used by detectors to find out the source of a change in an auditor to block changes arriving by unauthenticated mechanisms (e.g. plain email where headers can be faked). The property db.tx_Source has the following values: * None - Default value set to None. May be valid if it's a script that is created by the user. Otherwise it's an error and indicates that some code path is not properly setting the tx_Source property. * "cli" - this string value is set when using roundup-admin and supplied scripts. * "web" - this string value is set when using any web based technique: html interface, xmlrpc .... * "email" - this string value is set when using an unauthenticated email based technique. * "email-sig-openpgp" - this string value is set when email with a valid pgp signature is used. (*NOTE* the testing for this mode is incomplete. If you have a pgp infrastructure you should test and verify that this is properly set.) This also includes some (possibly incomplete) tests cases for the modes above and an example of using ts_Source in the customization.txt document.