Note: although I hopefully fixed all the conflicts,
some tests are quite broken.
Conflicts:
borg/_chunker.c
borg/archive.py
borg/archiver.py
borg/cache.py
borg/helpers.py
borg/testsuite/archiver.py
one of the biggest issues with borg < 1.0 was that it had a default target chunk
size of 64kiB, thus it created a lot of chunks, a huge chunk management overhead
(high RAM and disk usage).
Note: there is a failing archiver test on py33-only now.
It is somehow related to __del__ method usage in Cache
and/or locking code. Could not find out the exact reason
why it behaves like that.
outdated - it just showed different levels of zlib compression,
but not we additionally have "lzma", "lz4" and "none" compression.
the "usage" and "internals" docs give some hints about them, too.
also: add some benchmarking output showing singlethread, multithread and
multithread-with-gil-releasing-chunker performance.
this changeset maybe improves multithreading performance a little, about 3%
(but that might be close to the measurement accuracy).
