Document that TTL <= 0 means no TTL
Improve handling of range tomsbstones for wide partitions

patch by m0nstermind; reviewed by slebresne for CASSANDRA-6446
Merge branch 'cassandra-2.1' of https://git-wip-us.apache.org/repos/asf/cassandra into cassandra-2.1
Changelog fix
Fix bad merge
Fix test for change in CASSANDRA-6357
Silence errors about java agent in debian scripts.
Patch by Federico Piccinini, reviewed by brandonwilliams for
CASSANDRA-6775
Merge branch 'cassandra-2.0' into cassandra-2.1
update changes
Merge branch 'cassandra-1.2' into cassandra-2.0
Merge branch 'cassandra-2.0' into cassandra-2.1
Fix ClassCastException for compact table with composites

patch by slebresne; reviewed by iamaleksey for CASSANDRA-6738
Pool CqlRecordWriter clients by inetaddress rather than Range
patch by Christian Rolf; reviewed by jbellis for CASSANDRA-6665
merge from 2.0
kill startup on incompatible sstable instead of continuing and failing later
Fix compaction_history timestamps
patch by Chander Pechetty and jbellis for CASSANDRA-6784
merge from 2.0
r/m populate_io_cache_on_flush from yaml (per-table since #4694)
merge from 1.2
Merge branch 'cassandra-2.0' into cassandra-2.1