Fix typo

Thanks to @saramcardle for noticing!

Closes #3.

Author: ctrueden

src/main/java/_3D_OC_Options.java

@@ -85,7 +85,7 @@ public void run(String arg) {
     gd.addMessage("");
     gd.addMessage("Image parameters:");
     gd.addCheckbox("Close_original_images_while_processing_(saves_memory)", closeImg);
-    gd.addCheckbox("Show_masked_image_(redirection_requiered)", showMaskedImg);
+    gd.addCheckbox("Show_masked_image_(redirection_required)", showMaskedImg);
     gd.addMessage("");
     gd.addMessage("Maps' parameters:");
     gd.addNumericField("Dots_size", dotSize, 0);
@@ -128,4 +128,4 @@ public void run(String arg) {
 }
 
 
-}
+}