- table_after_join_selectivity() should use records_init (new bug)
- get_examined_rows() changed to double to get similar results
  as in MariaDB 10.11
- Fixed bug where table_after_join_selectivity() did not correct
  selectivity in the case where a RANGE is used instead of a REF.
  This can happen if the range can use more key_parts than the REF.
  WHERE key_part1=10 and key_part2 < 10

Other things:
- Use JT_RANGE instead of JT_ALL for RANGE access in all parts of the code.
  Before we used JT_ALL for RANGE.
- Force RANGE be used in best_access_path() if the range used more key
  parts than ref. In the original code, this was done much later in
  make_join_select)(). However we need to know in
  table_after_join_selectivity() if we have used RANGE or not.
- Added more information about filtering to optimizer_trace.