[NTG-context] [PATCH] Small improvement for 'setuptex'

Hello. I'm using standard 'setuptex' file to set apropriate variables for my shell. I'd like to suggest small improvement for this file. See attached patch. P.S. The real use of this file is in my shell initialization scripts. It is sourced in specific way so I faced a situation when 'export' is required. Besides that unsetting unused variables also good habit to interactive session. --- WBR, Vladimir Lomov -- Violence is molding.