Some symbols have fewer attributes in OMOBJ tag than most others #41

Most of the symbols define in the ocd-files in https://github.com/OpenMath/CDs/tree/master/cd/Official have three attributes in their <OMOBJ> tag, like the following:
<OMOBJ xmlns="http://www.openmath.org/OpenMath" version="2.0" cdbase="http://www.openmath.org/cd">.

However, there are several symbols which do not comply with this "rule". Some symbols do not have an <OMOBJ> at all (probably by design). Others have this tag but without the cdbase and the version attribute.

To get an overview, I wrote a little script, generating an yaml-file with the results represented like this:

- path: CDs/cd/Official/relation3.ocd
  name: is_transitive
  omobj_attr_cdbase: None
  omobj_attr_version: '2.0'
  omobj_attr_xmlns: http://www.openmath.org/OpenMath
  omobj_tag_present: true
- ...

(see https://github.com/cknoll/openmath-cd-analysis for the script and its resulting yaml-file).

At the moment I only have limited understanding of OpenMath CDs but I think this (seemingly inconsistent) lack of attributes for some symbols is probably not by design. At least it hinders my usecase of automatic URI-generation for each symbol.

If desired I think I can provide a PR adding the missing attributes.