Split MiscTest into RelationalMiscTest and JdbcMiscTest.

- All misc. tests except the ones for "fake" nullability can run against
  RelationalProfile.
- The IfThen clauses in ConditionalExpr nodes were in reverse order for
  no good reason. Changing to declaration order.
- Support ConditionalExpr and Like in QueryInterpreter
Switch NestingTest and NewQuerySemanticsTest to RelationalProfile.

- Fix bug in RewritePaths: Eliminate duplicate column names from the
  type that gets generated for a table.
- Support *, Not and Union in QueryInterpreter.
- Use the real HeapTable column ordering instead of the computed type for
  a table in QueryInterpreter.
Switch PagingTest and PrimaryKeyTest to RelationalProfile.

- Add uniqueness checks to HeapBackend via hash indices.
Split up ScalarFunctionTest into Relational and Jdbc parts.

- Add support for lots of numerical and other scalar functions to
  QueryInterpreter.
- Beef up ScalaNumericType to support that better.
- Fix hierarchy of BaseColumnType in RelationalProfile
Switch UnionTest and TemplateTest to RelationalProfile.

- Support Library.In and QueryParameter in QueryInterpreter.
- Fix parameter passing bug when using QueryExecutor to run applied
  parameterized queries.
- Pass query parameters to QueryInterpreter.