Fix ut-atomic_stats not including stats.h.
Add rudimentary support for peek, skip and skip_back in compressed streams.
tpie/cstream.h: Remove reference to file_base.
Add comment about m_streamBlocks.
Add comment about m_streamBlocks.
Fix truncate not flushing the dirty block.
Fix truncate not updating m_streamBlocks properly.
Fix unused variable warnings in ami::stream.

(cherry picked from commit 8612ed7018989c642af5611349dcc8a561502e80)
Implement methods peek, skip and skip_back in file_stream.

(cherry picked from commit 174c0722b2c764d4a991e4e47eb243faa2c1a110)
Add documentation.

(cherry picked from commit 0129378bb2a872a2ccac2f00dc12edb639a3b559)
Change file_stream::read to peek and skip.

(cherry picked from commit fa6a52c4c49efe957b893214b37cf2239c8d886f)
Change read_back to skip_back and peek.

(cherry picked from commit 7f71fd04a51abba585ea41452e74598045d772e3)
Import file_stream::peek/skip from master branch
Rename read_request::read_direction -> get_read_direction, and tpie::direction -> read_direction.
Get rid of tpie/pipelining/CMakeLists.txt.

(cherry picked from commit b3f82250aea422b60c13b6a9ffe9105c5ea6ac51)

Conflicts:
	tpie/pipelining/CMakeLists.txt
Add pipelining/merge_sorter.cpp to CMakeLists.txt.
Remove pipelining/join.h from CMakeLists.txt (needs to be readded when merging into master).
Fix truncate_zero.
Make peek, read, read_back return const references and get rid of *_ref
Make stream and stack use read/read_back instead of read_ref/read_back_ref.