4e172c93f9
As discussed in GitHub issue #624 Lua scripts should not use variables that are never going to be read, because the memory for variable names is never going to be freed. Add an optional `ifexist` parameter to the `set_var` function that allows a Lua developer to set variables that are going to be ignored if the variable name was not used elsewhere before. Usually this mean that there is no `var()` sample fetch for the variable in question within the configuration.