Rewrite into to para 4 in 2.1 per comments

from astronomeralex
I think fitsverify is part of FTOOLS
Add reference to JPEG2000 paper
Minor typo corrections
Remove wrong reference to Paper III
Remove center command in verbatim environments that use the full text width
Try to integrate in redded text in Summary

Some sections back to Lession 3, others stick in summary
Small fixes to para in Lesson 3
Per multiple expressed opinions, moving encoding section

From 2.1.3 it is now 2.3.4.
Spelling fix in Summary
serialisation -> serialization per Webster
Put in itemized list of overview of problems

in the Summary.
Modify reference to paper II using same convention as in FITS distorsion paper
Remove paragraph in Intro on simulated/theory data in

FITS. In its current form, it doesnt appear to flow with
the argument in the introduction.
No real NOAO error model, remove mention
Add Lesson on conventions vs standards
Make Lesson 4 a subsection of discussion
Two slight tweaks in the abstract:

1. comma -> semicolon

2. This one I'm not 100% sure on, but I don't like that the last
   clause uses "hope" twice.  I changed the first "we hope" to, "it is"
   where "it" refers to our intentions.  Still not sure if that's the
   clearest approach though.
To say that HIERARCH cards make use of COMMENT keywords is innacurate.  Rather, they use commentary keywords which are syntactic feature of the format reserved primarily for COMMENT and HISTORY keywords.  But HIERARCH itself is a commentary keyword albeit not one specifically mentioned by the standard.
Merge pull request #30 from embray/comment-commentary

  Correction on HEIRARCH