fix metadata for earlier mysql (pingcap#172)

* fix metadata for earlier mysql

* add UT

* delete showMasterStatusNum

improve dumpling error info (pingcap#156)

* add sql in error info

* can specify where and sql at the same time

* refine

Unify `--filesize` and `--statement-size` definition with mydumper's (p…

…ingcap#142)

* reduce bound address times to save more time

* tmp

* unify file size

* fix ut

* fix bug that escapeBackSlash not used for rows arguments

* tmp

* move filesize and statementsize argument to writepipe

* fix format

* address comment

fix consistency bug (pingcap#128)

* fix consistency problem

* add consistency integration test

* address comment

* address comments

parse tso for snapshot (pingcap#124)

parse tso for snapshot (pingcap#124)

dumpling v4.0.2