[David Aggeler <david_aggeler@xxxxxxxxxx>]

In my opinion the numerous checks for check_col() in the dissectors.are 
superfluous (and confusing).
All col_set_xxxx() functions in column-utils.c correctly check for the 
precondition.
And the precondition is better placed in column-utils.c. Once done, 
removing the export would be the logical consequence.

As I don't have direct SVN access and since I'm not core member, I'm not 
sure whether I should start this change.
Would a single .diff file do? Any objection or motivation do do so?

David