* develop: (41 commits)
  [TD-519] fix execute sql return
  fix crash caused by double free when fail to initQInfo
  fix: jdbc resultset
  [TD-314] modify python connector to adapt C API
  [td-225] add query cost statistics.
  [TD-314] modify python connector to adapt the taos API change
  test: importOneRow
  [td-225] update script
  [td-225] update script
  [td-225] update script
  [td-225] update the slow query buffer
  feat: taosdemo, taosdump
  [td-225] fix memory leaks.
  [td-225] add query cost summary right before the qinfo is destoried.
  [td-225] fix memory leaks
  [td-225] update the output log format
  [td-225] fix bugs found by script
  [td-225] handle super table missing error
  [td-225] fix invalid write
  [td-225] fix memory leaks
  ...