oxtradoc needs to handle xml2rfc v2 restrictions

[philshafer]

As a general comment, oxtradoc needs to handle xml2rfc v2 restrictions. V2 was rewritten in python and is much nicer, but enforces restrictions that V1 did not.

anchors can't start with numeric

Andy Bierman writes:

draft-ietf-netconf-restconf-06.xml: Line 4849: Syntax of value for
attribute anchor of section is not valid

That line is:

So the xml2rfc-v2 doesn't like anchor identifiers that start
with numbers. Adding a leading "x" makes it work. I'll fix
oxtradoc to stop auto-generating these when the title starts
with a digit. The work-around is to add a manual anchor, like:

** 04 - 05 @D05@

tabs must be expanded

WARNING: Text around line 2588 contains tab characters. These will be expanded, assuming
a tab-size of 8.

A zillion of these can wreck your day. oxtradoc should expand tabs.