added createThumbnail() to ImageUtil
addad getBitmap()       to ImageUtil

thumbnail creation is much faster now!

	modified:   nomacs/src/org/nomacs/android/nomacs/ImageActivity.java
	modified:   nomacs/src/org/nomacs/android/nomacs/ImageBrowserActivity.java
	modified:   nomacs/src/org/nomacs/android/nomacs/util/ImageUtil.java