Fix Issue #28 - Merge MailScanner Rule Editor into Mailwatch

Merges MSRE (http://msre.sourceforge.net) into Mailwatch.

Please read the INSTALL doc at root of tree, and INSTALL docs in tools/MailScanner_rule_editor and tools/Cron_jobs

HTML formatting could be nicer, and it's not guaranteed to be bug-free.

Fixes over original MSRE:

1: Rules with 'action' of 0 are now correctly handled (as in size rules).

2: Rule descriptions start immediately after the # character. This stops MSRE from chopping off 1st character of comments which weren't generated by MSRE.

3: Treat blank lines in rules as comments

4: Sort rule file names into alphabetical order before listing

5: Requires authenticated MailWatch Admin user to be able to edit rules (this is why I integrated it into MailWatch)

6: Allow "Virus:" keyword in rule files

7: Fix the original MSRE's very broken 'and' handling

8: Do not allow user to change a default rule into any other type of rule

9: Fix posting of escaped data in forms

10: Fix case-sensitivity in keywords like "FromOrTo:"