updated string ids

src/org/geometerplus/fbreader/library/AuthorTree.java

@@ -43,7 +43,7 @@ public class AuthorTree extends LibraryTree {
 
 	@Override
 	protected String getStringId() {
-		return getName() + ":" + getSortKey();
+		return "@AuthorTree" + getName() + ":" + getSortKey();
 	}
 
 	@Override

src/org/geometerplus/fbreader/library/BookTree.java

@@ -54,7 +54,7 @@ public class BookTree extends LibraryTree {
 
 	@Override
 	protected String getStringId() {
-		return getName();
+		return "@BookTree " + getName();
 	}
 
 	@Override

src/org/geometerplus/fbreader/library/SeriesTree.java

@@ -40,7 +40,7 @@ public final class SeriesTree extends LibraryTree {
 
 	@Override
 	protected String getStringId() {
-		return getName();
+		return "@SeriesTree " + getName();
 	}
 
 	BookTree getBookInSeriesSubTree(Book book) {

src/org/geometerplus/fbreader/library/TagTree.java

@@ -39,7 +39,7 @@ public final class TagTree extends LibraryTree {
 
 	@Override
 	protected String getStringId() {
-		return getName();
+		return "@TagTree " + getName();
 	}
 
 	protected String getSortKey() {

src/org/geometerplus/fbreader/library/TitleTree.java

@@ -59,7 +59,7 @@ public final class TitleTree extends LibraryTree {
 
 	@Override
 	protected String getStringId() {
-		return getName();
+		return "@TitleTree " + getName();
 	}
 
 	@Override