EBookBackendSqliteDB: Adding cursor APIs

EBookBackendSqliteDB: Adding cursor APIs

Added the following APIs:

      o e_book_backend_sqlitedb_cursor_new()

        Creates a cursor for a given query expression and sort order

      o e_book_backend_sqlitedb_cursor_free()

        Frees a cursor and it's resources

      o e_book_backend_sqlitedb_cursor_move_by()

        Moves the cursor and fetches results

      o e_book_backend_sqlitedb_cursor_set_target()

        Sets the cursor state to a given position in the results

      o e_book_backend_sqlite_cursor_calculate()

        Calculates the position / total values of a cursor.

      o e_book_backend_sqlitedb_cursor_set_sexp()

        Sets the search expression for a given cursor

Also restored DB overwrite when country code changes.