mark up classes and methods
Fix typo
Note serialisations are architecture independent and should be portable within a release series
Use () on method names in :xapian-method: and :xapian-just-method:
Use :xapian-constant: rather than :xapian-method: for a couple of constants
Fix typo
Wording tweak
Prune oldmanual text which is already convered, and start to add todo items