add iterateEval method
Add process1.delete
add append option to fileChunkW
Merge pull request #263 from ezhulenev/append-to-file

Add append option to fileChunkW
Merge pull request #238 from jilen/generalize_iterate

generalize iterate method
Merge pull request #247 from fthomas/delete

Add process1.delete
Document io.fileChunkW's append parameter