message: Add rename column instruction to AFL.
diff: @@ -65,6 +65,7 @@ enum INS {
  INSERT_ROW,
  ADD_EMPTY_ROW,
  INSERT_COLUMN,
  + RENAME_COLUMN,
  ADD_COLUMN,
  REMOVE_COLUMN,
  SET,
  @@ -338,6 +339,19 @@ void parse_and_apply_instructions(std::string& in, const std::string& path, util
  t->remove_column(col_ndx);
  }
  }
  + else if (instr == RENAME_COLUMN && g.size() > 0) {
  + size_t table_ndx = get_next(s) % g.size();
  + TableRef t = g.get_table(table_ndx);
  + if (t->get_column_count() > 0) {
  + size_t col_ndx = get_next(s) % t->get_column_count();
  + std::string name = create_column_name(s);
  + if (log) {
  + *log << "g.get_table(" << table_ndx << ")->rename_column("
  + << col_ndx << ", " << name << ");\n";
  + }
  + t->rename_column(col_ndx, name);
  + }
  + }
  else if (instr == MOVE_COLUMN && g.size() > 0) {
  size_t table_ndx = get_next(s) % g.size();
  TableRef t = g.get_table(table_ndx);
  