This reverts #722 and should make IO.binwrite no longer truncate the file when passed an offset.
Also has a commit from @enebo that never seemed to make it from the jruby.org repo to github...not sure how that happened.
Update to use official 1.0.10 version of jcodings
Revert "REFACTORING: supporting flag about receiving an offset or not."
This reverts commit 05de78e.
IO.binwrite doesn't truncate the file if an offset is given