pyloxi: add padding as its own member type

Also remove it from pretty-printing.
diff --git a/py_gen/templates/_pack.py b/py_gen/templates/_pack.py
index 15645ee..66ee763 100644
--- a/py_gen/templates/_pack.py
+++ b/py_gen/templates/_pack.py
@@ -26,7 +26,7 @@
 :: # under the EPL.
 ::
 :: # TODO coalesce format strings
-:: from py_gen.codegen import Member, LengthMember, TypeMember
+:: from py_gen.codegen import Member, LengthMember, TypeMember, PadMember
 :: length_member = None
 :: length_member_index = None
 :: index = 0
@@ -35,6 +35,8 @@
 ::         length_member = m
 ::         length_member_index = index
         packed.append(${m.oftype.gen_pack_expr('0')}) # placeholder for ${m.name} at index ${length_member_index}
+::     elif type(m) == PadMember:
+        packed.append('\x00' * ${m.length})
 ::     else:
         packed.append(${m.oftype.gen_pack_expr('self.' + m.name)})
 ::     #endif
diff --git a/py_gen/templates/_unpack.py b/py_gen/templates/_unpack.py
index 6003725..91186cc 100644
--- a/py_gen/templates/_unpack.py
+++ b/py_gen/templates/_unpack.py
@@ -26,8 +26,11 @@
 :: # under the EPL.
 ::
 :: # TODO coalesce format strings
-:: from py_gen.codegen import Member, LengthMember, TypeMember
+:: from py_gen.codegen import Member, LengthMember, TypeMember, PadMember
 :: for m in ofclass.members:
+::     if type(m) == PadMember:
+::         continue
+::     #endif
 ::     unpack_expr = m.oftype.gen_unpack_expr('buf', m.offset)
 ::     if type(m) == LengthMember:
         _length = ${unpack_expr}