Stuff in "merge" that is not in "master" minus minor changes:

dummy acl and xattr implementation for unsupported platforms
give specific path to xattr.is_enabled(), disable symlink setattr call that always fails
less memory usage: do not create items_buffer and chunker unless we are creating new archive
fix misleading hint the fuse ImportError handler gave, fixes #237
source: misc. cleanups, pep8, style
serve: use os.write(stdout_fd, ...), fixes #233
implement attic check --last N
check: sort archives in reverse time order
avoid defect python-msgpack releases, fixes #171, fixes #185
check unpacked data from RPC for tuple type and correct length, fixes #127
Cache: do not try to release the lock twice
less memory usage: add global option --no-cache-files
fix traceback when trying to do unsupported passphrase change, fixes #189
datetime does not like the year 10.000, fixes issue #139
docs improvements, fixes, updates
cleanup crypto.pyx, make it easier to adapt to other modes
attic extract: if --stdout is given, write all extracted binary data to stdout
attic create: if "-" is given as path, read binary from stdin
do os.fsync like recommended in the python docs
Extra debug information for 'fread failed'
FUSE: reflect deduplication in allocated blocks
Only allow whitelisted RPC calls in server mode
Normalize source/exclude paths before matching