Support table functions in SQL

[henneberger]

Initial support for table functions in SQL. Supports calling sqrl table functions but does not impart sqrl native table paths.

IMPORT ecommerce-data.Orders;
X(@id: Int) := SELECT * FROM Orders WHERE id = @id;
X(@id: Int, @customerid: Int) := SELECT * FROM Orders WHERE id = @id AND customerid = @customerid;
Y(@id: Int) := SELECT * FROM TABLE(X(2));
Z(@id: Int) := SELECT * FROM TABLE(X(2, 3));

IMPORT ecommerce-data.Orders;
X(@id: Int) := SELECT * FROM Orders WHERE id = @id;
Y(@id: Int) := SELECT * FROM TABLE(X(@id));
Z := SELECT * FROM TABLE(Y(3));

[mbroecheler]

This is awesome - thanks for getting this to work. It really highlights our contributions to SQL by being able to reuse those functions. Well done!
One minor nit.

[mbroecheler]

This should call a helper function. We should already have one for this.

[henneberger]

Removed in next commit