Minor tweaks

I realized during the process of importing directly from files, if the user were to add brush files to a brush list folder that already has a Brush2.ini or brush_script or brush_bitmap, duplicate files would not be handled. This could result in brush files being overwritten within the brush list folder, but would not affect the user's actual brush files and brush config files besides importing over a possibly incorrect file.

I implemented automatic renaming of duplicate files when loose brush files are added into a brush list folder regardless of the contents within a brush list folder (e.g. like if there's a brush_script/brush_bitmap folder or Brush2.ini file already present) to address this.