Added variable ARIA_CHECKPOINT_LOG_ACTIVITY to allow one to specify how often we should do a checkpoint.
Added more error printing to log if log_warnings > 2
Give an error if checkpoint record is not correct,

mysql-test/suite/maria/r/compat_aliases.result:
  Added ARIA_CHECKPOINT_LOG_ACTIVITY
mysql-test/suite/maria/r/maria3.result:
  Added ARIA_CHECKPOINT_LOG_ACTIVITY
storage/maria/ha_maria.cc:
  Added ARIA_CHECKPOINT_LOG_ACTIVITY
  Added more error printing to log if log_warnings > 2
  Added db and table name to error message when printing to log
storage/maria/ma_check.c:
  Fixed bug where we didn't reset some variables between repair() calls
storage/maria/ma_checkpoint.c:
  Made maria_checkpoint_min_activity global.
  Don't do checkpoint if no data logged.
  Changed test for if we should do checkpoint to test separately for if log has grown or if we have had a lot of of cache writes.
storage/maria/ma_recovery.c:
  Give an error if checkpoint record is not correct
storage/maria/trnman.c:
  Don't print not needed long_transaction_id entries for checkpoints.