Function:    EnvAdd()

               This function adds a string to the environment.
               Use this function in combination with EnvDel() to replace
               an environment string. Make sure there is enough
               room in the environment to hold the string (truncated
               otherwise), also make sure to not define the same
               variable twice.

  Syntax:      EnvAdd(cStr)

  Arguments:   cStr is the complete environment string to add.

  Returns:     Nothing.

  Usage:       EnvAdd('PROMPT=Enter "EXIT" to return$_$g$p')
               * (Ensure that a previous PROMPT was deleted)