merge by xiaomi

  RuleTimePrecision
  MySQL 5.6.4+ New time data type, support time precision to microsecond

fix #155 a new config arg 'min-cardinality' for index column selection

  column.Tp may be nil when checking

a new config arg 'min-cardinality' for index column selection

  syntax check now only use tidb parser, no vEnv dependency.

merge by xiaomi

  bit type not config as int, when two columns compare will
  give ARG.003 suggestion.

  fix #154, #157 by the way

  不建议使用连续判断
  SELECT * FROM tbl WHERE col = col = 'abc'

add COL.007 RuleMaxTextColsCount & update ARG.003 rule content

sync master

fix SetLooger && update filepath

add new heuristic rule RuleColumnNotAllowType COL.018

  compatible with windows file path, regression filepath.Join

  support allow-collates checks

  go test ./... -update

  ref: https://github.com/XiaoMi/soar/pull/147

  Thanks @xiyangxixian

  COL.015 text/blob default value only tobe `NULL`;
  COL.012 text/blob `NOT NULL` CONSTRAINT may be danagerous;

fix #141