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/Huawei.pm

@@ -30,6 +30,7 @@
 package SNMP::Info::Layer3::Huawei;
 
 use strict;
+use warnings;
 use Exporter;
 use SNMP::Info::Layer3;
 use SNMP::Info::IEEE802dot3ad;
@@ -111,14 +112,14 @@ $VERSION = '3.68';
 );
 
 sub vendor {
-    return "Huawei";
+    return "huawei";
 }
 
 sub os {
     my $huawei = shift;
     my $descr  = $huawei->description();
 
-    if ( $descr =~ /\b(VRP)\b/ ) {
+    if ( defined ($descr) && $descr =~ /\b(VRP)\b/ ) {
         return $1;
     }
     return "huawei";
@@ -135,7 +136,7 @@ sub os_ver {
     my $descr  = $huawei->description();
     my $os_ver = undef;
 
-    if ($descr =~ /Version\s            # Start match on Version string
+    if (defined ($descr) && $descr =~ /Version\s            # Start match on Version string
                    ([\d\.]+)            # Capture the primary version in 1
                    ,?                   # There may be a comma
                    \s                   # Always a space
@@ -570,7 +571,7 @@ These are methods that return scalar value from SNMP
 
 =item $huawei->vendor()
 
-Returns 'Huawei'.
+Returns 'huawei'.
 
 =item $huawei->os()