Fix warning message for undefined entry
Use SeparatedValueReader
Refactor to use SeparatedValue{Reader,Writer}

instead of implementing our own column order logic
Refactor split_file to use SeparatedValue{Reader,Writer}
Refactor to use SeparatedValueReader
Merge pull request #73 from apregier/refactor-with-svr

Refactor with separated value reader/writer
Merge pull request #71 from apregier/warning-message-fix

Fix warning message for undefined entry