[osis-core] Index

[Harry Plantinga]

A few ThML documents have <index> elements, specifying
that a spot in the text should go in a subject or other
index.

  <index type="subject" subject1="Christian Life" subject2="Sanctification"
  title="Apotheosis">The word apotheosis...</index>

For a few moments the following crossed my mind:

  <seg type="subject-index" n="Christian Life:Sanctification"
  resp="Apotheosis">

... but then my sanity was restored and I decided to drop
the indexing information.

-Harry