reduce garbage on codec flag deserialization

patch by belliottsmith reviewed by dbrosius for cassandra-7244
Improve javadoc for KeysIndex

patch by plin reviewed by dbrosius for cassandra-7253
allow num_tokens to be unspecified, as described in the yaml
Fixup for CASSANDRA-6914: null handling, ...

patch by slebresne; reviewed by thobbs for CASSANDRA-7155
Changelog fix
Increase compaction visibility

Patch by cnlwsu; reviewed by marcuse for CASSANDRA-7242.
Always reallocate buffers with HSHA.

Patch by brandonwilliams, reviewed by Rick Branson for CASSANDRA-6285
only query once for local host id on join

patch by dbrosius reviewed by jbellis for cassandra-7257
Merge branch 'cassandra-1.2' into cassandra-2.0
remove unused field 'severity'
Fix cql3 reader when columns is reversed.

Patch by Alex Liu, reviewed by pkolackzk for CASSANDRA-7100
Fix ConfigHelper.setInputColumnFamily with uppercased keyspace names.

Patch by Alex Liu, reviewed by pkolackzk for CASSANDRA-7093
Quote ks/cf names better.

Patch by Alex Liu, reviewed by brandonwilliams for CASSANDRA-7093
Fix 2ndary index queries with DESC clustering order

patch by slebresne; reviewed by thobbs for CASSANDRA-6950
Invalidate key cache on table drop

patch by thobbs; reviewed by slebresne for CASSANDRA-6525
Fix flapping RecoveryManagerTest

patch by benedict; reviewed by jbellis for CASSANDRA-7084
Add missing iso8601 patterns for date strings

patch by chander; reviewed by slebresne for CASSANDRA-6973
Support multi-row selects within a partition using IN

Patch by Tyler Hobbs; review by Sylvain Lebresne for CASSANDRA-6875