sql wall allow rename table
add test fro sql wall renameTableAllow
bugfix: parse error for 'alter table xx comment 'xx''
Merge remote-tracking branch 'upstream/master'
Merge pull request #508 from yakolee/master

improve sql parser & sql wall
fix issues #509
improve sql wall
modify version
Merge pull request #511 from yakolee/master

improve sql wall
Merge pull request #510 from jacking124/master

fix issues #509