GRIFFIN: symbol type cast for create table statement supports caching option and validates symbol capacity value

CAIRO: Null for symbol value now corresponds to null for int. This removes unnecessary complexity around implementing getInt()

CAIRO: bug fixes

GRIFFIN: initial limit implementation, e.g. select * from tab limit 10. It supports last N rows as well as first N rows. More testing to follow.

LINUX: C code refactoring to allow for different implementations of interrupting of blocking accept()

GRIFFIN: bugfixed NPE when select had fewer columns than target table needed and columns are ambiguous.

GRIFFIN: join implementations propagate timestamp column from master if it exists. ASOF join validates that both master and slave cursors have timestamp defined. Validation errors are reported using position of "join" keyword in query text and referring to left or right side of this join.