[td-225] update the max retry for sub query.

refactor tsdb log format

add test cases

* develop:
  scripts
  scripts
  [TD-149] fix compile error after merge develop
  [149] fix bug while replace sdb
  replace sdb func
  [TD-149] add callback func to cache
  scripts
  [TD-149] replace sdb hash
  [TD-149] change hash imp in sdb

Feature/hash

add test cases

# Conflicts:
#	src/vnode/src/vnodeMain.c

* develop: (21 commits)
  [td-225] fix bugs in multi-vnode projection query.
  support GCC 4.8
  [td-225]
  fix failed test cases
  [TD-161]
  [TD-161]
  [TD-161]
  avoid a potential bug
  tsdb notify the vnode about it status changes
  [td-225] refactor hash function
  [td-225] fix bugs for leastsquares query.
  [td-225] fix bugs at client
  [td-225] fix bugs for 256 columns data check
  use tbname in function tbid()
  single table subscribe is done
  super table subscribe is done
  build VgroupTableInfo
  fix typo
  add taosArrayClear
  enhance exception handling
  ...

support GCC 4.8

Feature/query

[TD-307]

Feature/subscribe

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