- made a number of substitutions case insensitive

- fixed sub headings, the parsing of bold words messed up sub
  headings.

- fixed too greedy replacement of bold and underlined text

- commented out & -> &amp; parsing as it messes up the HTML entity
  parsing. Must think of something cleverer ...

- org2atom now doesn't print org formatting characters in its
  summaries.

- added sed script to strip org mode text of its markup, this is useful
  for org2atom, among other tings.