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