Refactor existing adapters into a generic superclass

This commit also moves various blog classes into their own packages and
makes the required visibility changes.

briar-android/src/org/briarproject/android/util/BriarAdapter.java

@@ -0,0 +1,106 @@
+package org.briarproject.android.util;
+
+import android.content.Context;
+import android.support.annotation.Nullable;
+import android.support.v7.util.SortedList;
+import android.support.v7.widget.RecyclerView.Adapter;
+import android.support.v7.widget.RecyclerView.ViewHolder;
+
+import java.util.Collection;
+
+import static android.support.v7.util.SortedList.INVALID_POSITION;
+
+public abstract class BriarAdapter<T, V extends ViewHolder>
+		extends Adapter<V> {
+
+	protected final Context ctx;
+	protected final SortedList<T> items;
+
+	public BriarAdapter(Context ctx, Class<T> c) {
+		this.ctx = ctx;
+		this.items = new SortedList<>(c, new SortedList.Callback<T>() {
+			@Override
+			public int compare(T item1, T item2) {
+				return BriarAdapter.this.compare(item1, item2);
+			}
+
+			@Override
+			public void onInserted(int position, int count) {
+				notifyItemRangeInserted(position, count);
+			}
+
+			@Override
+			public void onRemoved(int position, int count) {
+				notifyItemRangeRemoved(position, count);
+			}
+
+			@Override
+			public void onMoved(int fromPosition, int toPosition) {
+				notifyItemMoved(fromPosition, toPosition);
+			}
+
+			@Override
+			public void onChanged(int position, int count) {
+				notifyItemRangeChanged(position, count);
+			}
+
+			@Override
+			public boolean areContentsTheSame(T item1, T item2) {
+				return BriarAdapter.this.areContentsTheSame(item1, item2);
+			}
+
+			@Override
+			public boolean areItemsTheSame(T item1, T item2) {
+				return BriarAdapter.this.areItemsTheSame(item1, item2);
+			}
+		});
+	}
+
+	public abstract int compare(T item1, T item2);
+
+	public abstract boolean areContentsTheSame(T item1, T item2);
+
+	public abstract boolean areItemsTheSame(T item1, T item2);
+
+	@Override
+	public int getItemCount() {
+		return items.size();
+	}
+
+	public void add(T item) {
+		items.add(item);
+	}
+
+	public void addAll(Collection<T> items) {
+		this.items.addAll(items);
+	}
+
+	@Nullable
+	public T getItemAt(int position) {
+		if (position == INVALID_POSITION || position >= items.size()) {
+			return null;
+		}
+		return items.get(position);
+	}
+
+	public int findItemPosition(T item) {
+		return items.indexOf(item);
+	}
+
+	public void updateItemAt(int position, T item) {
+		items.updateItemAt(position, item);
+	}
+
+	public void remove(T item) {
+		items.remove(item);
+	}
+
+	public void clear() {
+		items.clear();
+	}
+
+	public boolean isEmpty() {
+		return items.size() == 0;
+	}
+
+}