[Mobile] Border Mask Option

- Full > cards have round corners (both .fullborder and .full cards)
- Crop > .fullborder cards will be cropped to look like .full cards
- Off > no changes (for user who use png images use Off)

forge-gui/src/main/java/forge/properties/ForgePreferences.java

@@ -142,7 +142,7 @@ public class ForgePreferences extends PreferencesStore<ForgePreferences.FPref> {
         UI_DYNAMIC_PLANECHASE_BG("false"),
         UI_DISABLE_IMAGES_EFFECT_CARDS("false"),
         UI_ENABLE_PRELOAD_EXTENDED_ART("false"),
-        UI_ENABLE_BORDER_MASKING("false"),
+        UI_ENABLE_BORDER_MASKING("Crop"),
         UI_SHOW_FPS("false"),
         UI_NETPLAY_COMPAT("false"),
         UI_LOAD_UNKNOWN_CARDS("true"),