Include snippet of query in SyntaxError messages

Patch by Benjamin Lerer; reviewed by Tyler Hobbs for CASSANDRA-7111
Merge branch 'cassandra-2.1' into trunk
ninja fix comments in SharedExecutorPool
Merge branch 'cassandra-2.1.0' into cassandra-2.1
Merge branch 'cassandra-2.1' into trunk
Add missing table name to DROP INDEX responses

Patch and review by Tyler Hobbs and Aleksey Yeschenko for CASSANDRA-7539
Merge branch 'cassandra-2.1.0' into cassandra-2.1
Add missing table name to DROP INDEX responses

Patch and review by Tyler Hobbs and Aleksey Yeschenko for CASSANDRA-7539
memtable_cleanup_threshold and memtable_flush_writers defaults
patch by jbellis; reviewed by bes for CASSANDRA-7551
Merge branch 'cassandra-2.1.0' into cassandra-2.1
Merge branch 'cassandra-2.1' into trunk
add cast to float
Merge branch 'cassandra-2.1.0' into cassandra-2.1
Merge branch 'cassandra-2.1' into trunk
reorder to avoid NPE
Merge branch 'cassandra-2.1.0' into cassandra-2.1
Merge branch 'cassandra-2.1' into trunk
Bump CQL version to 3.2.0 and update CQL docs

Patch by Tyler Hobbs; reviewed by Aleksey Yeschenko for CASSANDRA-7527
Merge branch 'cassandra-2.1.0' into cassandra-2.1
Bump CQL version to 3.2.0 and update CQL docs

Patch by Tyler Hobbs; reviewed by Aleksey Yeschenko for CASSANDRA-7527