Support for Canon CRW files

Thanks John,

A dream comes true, I got gqview to load Canon CRW files without
having to hack gdk-pixbuf (i.e. way faster). Here is a screenshot:

http://turingmachine.org/~dmg/temp/gqview/gqview_canon_crw_support.png


The patch is attached.

Some comments.

It looks like sometimes the raw handler does not get a file descriptor
(fd == -1). I noticed this too late, so my code is duplicated to deal
with each case (when I have a file, I read the file, when I don't, I
use the data in memory).

TODO

* refactor/cleanup the code. I suggest the creation of a file for
  Canon specific issues. 

* Test it with other cameras (I only have Canon d60 files, somebody
  with a Digital Rebel--first generation--, or a EOS 1d?)

* Add support for CR2 files.


For anybody who wants to try my code here is a file: 

http://turingmachine.org/~dmg/temp/gqview/dmg_040831_4209.CRW





--
Daniel M. German                  "Security is not a product
                                   that can be purchased off the shelf,
                                   but consists of policies, people,
    Kevin Mitnick ->               processes, and technology."
http://turingmachine.org/
http://silvernegative.com/
dmg (at) uvic (dot) ca
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