documentation overhaul (#353)

* ident
* remove $Id$ tags from rcs software which has been retired
* make an effort to sync required mib docs with actual code
* sync even more docs with what code actually does
* some whitespace nits
* fixup example to use snmpv2 for all but the most ancient devices
* remove blurb to find more specific snmp::info classes for classes
  which alrdy are as specific as they can get (eg snmp::info::layer3::vmware
  doesn't need info on to find a specific module since there ain't none)
* rename all sub {vendor} strings to lowercase vendor, if cisco, juniper
  and arista can be lowercase, so can be all the rest.
* fix tests
* spread some use warnings around
* use $ instead of @
* remove defines that are included via parent classes
* use strict + warnings
* remove alrdy included modules
* add comma after last list item
* typos
* mibs are found in our mib repo, not on the cisco site
* documentation fixes

lib/SNMP/Info/Layer2/Catalyst.pm

@@ -1,5 +1,4 @@
 # SNMP::Info::Layer2::Catalyst
-# $Id$
 #
 # Copyright (c) 2002,2003 Regents of the University of California
 # Copyright (c) 2008 Max Baker changes from version 0.8 and beyond
@@ -32,6 +31,7 @@
 package SNMP::Info::Layer2::Catalyst;
 
 use strict;
+use warnings;
 use Exporter;
 use SNMP::Info::CiscoStack;
 use SNMP::Info::Layer2::Cisco;
@@ -64,7 +64,7 @@ $VERSION = '3.68';
     %SNMP::Info::CiscoStack::MUNGE,
 );
 
-# Overidden Methods
+# Overridden Methods
 
 # i_physical sets a hash entry as true if the iid is a physical port
 sub i_physical {