REQUEST: user configurable timestamp position in auto-generated demos

When we use sv_demoAutoRecord the server will append a timestamp to the end of the demo name. I'd like to request a new cvar that allows the user to choose the format of the auto-generated demo names. Or, in the very least, the possibility of choosing between using the timestamp as a prefix, instead of a suffix.

The reason I want this is because it would make sorting demos by date much easier. Specially when playing a sequence of non-alphabetically sorted maps. "start" -> "e1m1" is a great example of that.

Currently it is possible to use variables as the demo prefix, using sv_demoAutoPrefix. Unfortunately FTE does not have a $timestamp variable, so the best I was able to come up with was to set sv_demoAutoPrefix to $date. FTE does have a $time variable, but the precision is only up to minutes and it uses : as a separator, which generally not allowed in filenames.

In my particular case, creating a $timestampvariable that outputs date and time in the same format FTE uses to generate the demo name would solve everything.