There is no way to Flush() encoders without closing them

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Once an encoder is closed, it cannot be written to, and there is no way to 
get ALL of the data that has been written to an encoder and then resume 
encoding as normal.

I've added a WritePartialBits public method that will allow a user to write the 
buffered partial bits to a secondary writer. This allows one to retrieve all 
necessary data at any given point while still retaining the ability to encode 
without recreating the encoders.

I don't use mercurial much, but my changes are in the default branch of 
bitbucket.org/m_coffin/deltagolomb. You should be able to pull them from there.

Original issue reported on code.google.com by [email protected] on 28 Aug 2014 at 12:54