Support decimal types in prepared statements

[aris-koning]

With the new extended C signature for monetdbe_prepare it is now possible determine the underlying implementation type of a value and bind it to a numerical type.

For example

CREATE TABLE test (x DECIMAL(15,5));
PREPARE SELECT x FROM test WHERE x > ?;

Say that we would like to bind the decimal value 10000.55555. Recently monetdbe_prepare can return a table with type info for each input and output parameter of the prepared statement. In this case it returns amongst others the scale 5 and implementation type short from which we can determine the short value to be bound which is 1000055555.

The Connection object API should be extended such that it can sensibly handle this new type info in order to correctly bind decimal values.