Changed error classes to inherit from StandardError instead of Exception.

This should make them easier to use with irb.

lib/net/ber.rb

@@ -33,7 +33,7 @@ module Net
 
   module BER
 
-  class BerError < Exception; end
+  class BerError < StandardError; end
 
 
   class BerIdentifiedString < String

lib/net/ldap.rb

@@ -261,7 +261,7 @@ module Net
 
   class LDAP
 
-    class LdapError < Exception; end
+    class LdapError < StandardError; end
 
     VERSION = "0.1.0"
 

lib/net/ldap/pdu.rb

@@ -31,7 +31,7 @@
 module Net
 
 
-class LdapPduError < Exception; end
+class LdapPduError < StandardError; end
 
 
 class LdapPdu

lib/net/snmp.rb

@@ -94,7 +94,7 @@ module Net
     end
 
     class SnmpPdu
-	class Error < Exception; end
+	class Error < StandardError; end
 
 	PduTypes = [
 	    :get_request,