rds 0.18 released

New features in rds 0.18:

- Choice types are a new category of types with a more compact syntax and a better run-time performance than union types. For choice types, the read() methods work with a switch statement instead of the backtracking trial-and-error approach used for unions.

- In the generated HTML documentation, package links in the top left window no longer work as toggles, making the look and feel more like Javadoc and more intuitive.

- The -ext option is no longer required and no longer supported. Extensions now use the JDK service provider mechanism (META-INF/services + java.util.ServiceLoader). All extensions are discovered as long as all JARs are on the class path or in the same folder when rds is invoked with the java -jar option.

- Functions may return compound types, not just integer types.

Bugfixes:

- Automatic offset calculation for labels in the write() method now works even in complicated situations where the size of a type depends on function calls and parent member references.

- In SQL tables, integer members are no longer represented as BLOBs. This was a bug introduced in 0.16.

The documents DataScript Language Overview and Installation Guide have both been updated to reflect the current status of rds 0.18, including the new features introduced in 0.16 and before.