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/Layer3/C3550.pm

@@ -1,5 +1,4 @@
 # SNMP::Info::Layer3::C3550
-# $Id$
 #
 # Copyright (c) 2008-2009 Max Baker changes from version 0.8 and beyond.
 # Copyright (c) 2004 Regents of the University of California
@@ -105,7 +104,7 @@ sub ports {
     return $ports;
 }
 
-#  Verions prior to 12.1(22)EA1a use the older CiscoStack method
+#  Versions prior to 12.1(22)EA1a use the older CiscoStack method
 #  Newer versions use the ETHERLIKE-MIB to report operational duplex.
 #  See http://www.ciscosystems.com/en/US/products/hw/switches/ps646/prod_release_note09186a00802a08ee.html
 
@@ -228,11 +227,6 @@ These devices run IOS but have some of the same characteristics as the
 Catalyst WS-C family (5xxx,6xxx).  For example, forwarding tables are held in
 VLANs, and extended interface information is gleaned from F<CISCO-SWITCH-MIB>.
 
-For speed or debugging purposes you can call the subclass directly, but not
-after determining a more specific class using the method above.
-
- my $c3550 = new SNMP::Info::Layer3::C3550(...);
-
 =head2 Inherited Classes
 
 =over