Remove Shell invocation as many as possible (high cost in term of speed of execution)

Sources/ResgenSwift/Generate/Generate.swift

@@ -46,9 +46,10 @@ struct Generate: ParsableCommand {
         // Execute commands
         configuration.runnableConfigurations
             .forEach {
+                let begin = Date()
                 $0.run(projectDirectory: options.projectDirectory,
                        force: options.forceGeneration)
-                print("\n")
+                print("Took: \(Date().timeIntervalSince(begin))s\n")
             }
 
         print("[\(Self.toolName)] Resgen ended")

Sources/ResgenSwift/Generate/Runnable/ImagesConfiguration+ShellCommandable.swift

@@ -12,7 +12,7 @@ extension ImagesConfiguration: Runnable {
         var args = [String]()
         
         if force {
-            args += ["-F"] // Images has a -f and -F options
+            args += ["-f"] // Images has a -f and -F options
         }
         
         args += [