Untested code for IRRDB prefix updates

This alternative uses arrays rather than DB requests to do the heavy lifting.

Untested, written while watching presentations...
[BF] record debug option
Update foreign refs
[IM] Complete yesterday's optimisation work
[IM] Remove database method of prefix updates.

With the database doing the heavy lifting from a blank database:

Database time  : 20.271860837936
Processing time: 0.94397568702698
Network time   : 83.258119821548

and on an update run:

Database time  : 11.44893693924
Processing time: 1.1716868877411
Network time   : 82.974792003632

And with the script doing the heavy lifting from a blank database:

Database time  : 11.148242950439
Processing time: 1.0650501251221
Network time   : 81.734930992126

and on an update run:

Database time  : 1.7090458869934
Processing time: 0.10312080383301
Network time   : 85.016879796982

Thus, the database version is now confined to Git history ;)

I'm all about optimisation and performance. But even I must remind myself sometimes of the cost of a database query :/
Merge branch 'nf-irrdb-playground'
Fix small typo in peering matrix
Improve update-l2database.pl

* add & use adapted version of Net::SNMP::Mixin::Util::normalize_mac()
  (needed because one stray MAC was outputing as ASCII, untranslated)
* delete old copy of update-l2database.pl from sflow directory
* copy comment about testing status on switches from old sflow version,
  and add Extreme BD-8806 to list
* apply $do_nothing to *all* DB-affecting actions
* improve debug output layout and increase output
* replace a printf occurrence with print
* standardise whitespace
Add switch models to compat-comments in update-l2database.pl
Merge pull request #61 from rowanthorpe/peering-matrix-typo

Fix small typo in peering matrix
Update foreign refs
Merge branch 'inex-live'
[BF] Force these to lower case to avoid confusion
[IM] Make it clearer what the CMS login form is about.
Merge pull request #47 from rowanthorpe/update-l2database-fixes

Improve update-l2database.pl
[IM] Added per @rowanthorpe

See #62
> I would just add that I found adding that 'urlbase' value to the config has proved very helpful
> for skinning (I've referenced it several times in doc pages especially), and I suggest that
> perhaps it is worth adding that to application.ini.dist anyway, irrespective of its use for cms
> login...?
Merge branch 'master' of https://github.com/inex/IXP-Manager
[IM] made nocwww clickable on customer overview page
Changelog and version bump