compress/bzip2: implement bz2 encoder

[gopherbot]

by johnkgallagher:

All the other compress/* packages include both decompression and compression.
compress/bzip2 only supports decompression.

[minux]

Comment 1:

Labels changed: added priority-later, removed priority-triage, go1.1maybe.

Status changed to Accepted.

[gopherbot]

Comment 2 by aaron.l.france:

Any update on this?

[rsc]

Comment 3:

No.

[rsc]

Comment 6:

Labels changed: added go1.3maybe.

[rsc]

Comment 7:

Labels changed: added release-none, removed go1.3maybe.

[rsc]

Comment 8:

Labels changed: added repo-main.

[gopherbot]

Comment 9 by camilo.aguilar:

bonus points if it leverages parallelization.