Adding input file with font to generate (iso with colors) + adding an optional extension suffix on font extension

Sources/FontToolCore/FontToolHelper.swift

@@ -12,7 +12,6 @@ class FontToolHelper {
     static func getFontsFilenames(fromInputFolder inputFolder: String) -> [String] {
         // Get a enumerator for all files
         let fileManager = FileManager()
-        
         guard fileManager.fileExists(atPath: inputFolder) else {
             FontTool.exit(withError: FontToolError.inputFolderNotFound(inputFolder))
         }