maint: Edit local function duplicator(bind, conn, ...)

* diet/filter/prenorm.lua: Likewise.
* tests/test-filter-prenorm.lua: Likewise.
Merge branch 'master' of https://github.com/gflima/dietncl
maint: Add local function capture_max_min(link, conn) to prenorm.lua

* dietncl/filter/prenorm.lua: Likewise.
* tests/test-filter-prenorm.lua: Likewise.