Track max/min column names in sstables to be able to optimize slice queries.

Patch by marcuse and jbellis, reviewed by jbellis for CASSANDRA-5514
Dont throw UOE when calling shouldInclude in NamesQueryFilter - include all files instead
cqlsh: add custom prompt support

patch by Cyril Scetbon; reviewed by Aleksey Yeschenko for CASSANDRA-5539
Merge branch 'cassandra-1.2' into trunk

Conflicts:
	bin/cqlsh