Feature Request: Configurable FLSpew.txt Location

[IrateRedKite]

Allow users to configure the location of FLSpew.txt using a line in flplusplus.ini

[BC46]

There's a small problem implementing this as FL creates FLSpew.txt before it loads any plugins. I guess it's possible to move the file to the desired location after it's been created, but I'm not sure if this is a clean solution.