libs/web: add export() to template namespace, allows templates to export...

libs/web: add export() to template namespace, allows templates to export symbols to the calling view namespace, this is useful for includes defining shared procedures or variables

libs/web/luasrc/dispatcher.lua

@@ -237,6 +237,7 @@ function dispatch(request)
 		   write       = luci.http.write;
 		   include     = function(name) tpl.Template(name):render(getfenv(2)) end;
 		   translate   = function(...) return require("luci.i18n").translate(...) end;
+		   export      = function(k, v) if tpl.context.viewns[k] == nil then tpl.context.viewns[k] = v end end;
 		   striptags   = util.striptags;
 		   pcdata      = util.pcdata;
 		   media       = media;