</li><li>Support NULL with a type: @meta CALL CAST(NULL AS INT) should return INT.
See the ValueExpression.java (currently it returns the type of the value;
it could have it's own type/precision/scale optionally, for example when created from CAST,
which is implemented in Function.java).
</li><li>Improve documentation of system properties: only list the property names, default values, and description.
</li><li>Support running totals / cumulative sum using SUM(..) OVER(..).
</li><li>Improve object memory size calculation. Use constants for known VMs, or use reflection to call java.lang.instrument.Instrumentation.getObjectSize(Object objectToSize)