Added test for incoming via ssh.

make incoming work via ssh (issue139); move chunk code into separate module. Incoming ssh needs to detect the end of the changegroup, otherwise it would block trying to read from the ssh pipe. This is done by parsing the changegroup chunks. bundlerepo.getchunk() already is identical to localrepo.addchangegroup.getchunk(), which is followed by getgroup which looks much like what you can re-use in bundlerepository.__init__() and in write_bundle(). bundlerevlog.__init__.genchunk() looks very similar, too, as do some while loops in localrepo.py. Applied patch from Benoit Boissinot to move duplicate/related code to mercurial/changegroup.py and use this to fix incoming ssh.

use HG10UN header for uncompressed bundle - use HG10UN instead of HG11 for uncompressed bundles header - check HG10BZ for compressed bundle - better error handling for invalid header some notes: - people who created uncompressed bundle will no longer be able to use them (it could be fixed with hand-editing) - older hg cannot detect an uncompressed bundle (bzip2 decompression will fail).