Multisets and Arrays

This week's update makes a number of small alterations to Pyrrho's syntax, mostly to bring it better in line with the SQL standard. Specifically, array and multiset initialisation (if not using a subquery) uses [] instead of (). Subqueries are always introduced with a leading parenthesis as in (SELECT .., and are used in predicates such as IN, EXISTS, UNIQUE. The Open Source distribution has been moved back to .NET v2.0 so that it works with a larger set of Linux distributions.