There's no need to pass the result of tvb_get_ptr() as the 'value' in

There's no need to pass the result of tvb_get_ptr() as the 'value' in
proto_tree_add_string(): just use proto_tree_add_item().

Replace some tvb_get_ptr()s with tvb_get_ephemeral_string()s.

In a couple of places an hf variable was being used as the length in a call to
proto_tree_add_*().  Use the appropriate variable instead.

svn path=/trunk/; revision=35497