Portable does not work with really weird characters in the path

[barbeque-squared]

I'm making this a separate issue, while trying to reproduce #918 (which I couldn't) I ran into a not-sure-if-related issue with the portable:

How to reproduce:

1. download and extract the portable anywhere
2. edit the folder name to have the Unicode Replacement Character (U+FFFD) anywhere
3. start ultrastardx.exe

The error message having a question mark makes it looks suspiciously similar to #837 (and its fix, #904) and because it's logging the full path, and because I can't reproduce it on Linux, chances are it's because it's doing .ToNative somewhere ?

That, and/or one of the AnsiStr or whatever is getting involved somewhere. I took a quick look at UPlatform*.pas and UPath.pas and the "a lot of function have three (or sometimes more) versions" is definitely not a good sign, because 904/UFilesystem also has this.

It's also really great that instead of {$IFDEF MSWINDOWS} / {$ELSE} just once for some IPath "give me a string version" function, we have entire interfaces IFDEF/ELSE'd. I know it's a result of historic mess regarding string handling between platforms, but at the same time isn't helping in making any of this more readable.