add .gitignore

.gitignore

@@ -0,0 +1,23 @@
+/.gradle/
+/.nb-gradle/private/
+/jme3-core/build/
+/jme3-plugins/build/
+/jme3-desktop/build/
+/jme3-android-native/build/
+/jme3-android/build/
+/jme3-blender/build/
+/jme3-effects/build/
+/jme3-bullet/build/
+/jme3-terrain/build/
+/jme3-bullet-native/build/
+/jme3-jogg/build/
+/jme3-jbullet/build/
+/jme3-lwjgl/build/
+/jme3-networking/build/
+/jme3-niftygui/build/
+/jme3-testdata/build/
+/jme3-examples/build/
+/jme3-jogl/build/
+/dist/
+/jme3-bullet-native/bullet.zip
+/jme3-bullet-native/bullet-2.82-r2704/