Bug fixes to serializers

[Assaf Arkin <ar...@intalio.com>]

The following bug fixes have been commited to the CVS. Thanks for all
the people mentioned below for their contribution.

- Fixed processing instruction printing inside element content to not
  escape content. Reported by Mikael Staldal
  <d9...@d.kth.se>

- Added ability to omit comments.
  Contributed by Anupam Bagchi <ab...@jtcsv.com>

- Fixed bug in newline handling when preserving spaces.
  Contributed by Mike Dusseault <md...@home.com>

- Fixed state.unescaped not being set to false when entering
  element state.
  Reported by Lowell Vaughn <lv...@agillion.com>

- Fixed bug in startDocument not calling prepare.
  Reported by Mikael Staldal <d9...@d.kth.se>

- Fixed bug in isElement and made HTMLdtd public.
  Contributed by Eric SCHAEFFER" <es...@posterconseil.com>

- Added ability to omit DOCTYPE declaration.
  Reported by Lars Martin <la...@smb-tec.com>

arkin


-- 
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Assaf Arkin                                            www.intalio.com
CTO, Intalio Inc.                                       www.exolab.org