Merge pull request #93 from norman/fix-for-where-true

Ensure @last_column is cleared after visiting object

lib/arel/visitors/to_sql.rb

@@ -133,7 +133,7 @@ def visit_Arel_Nodes_SelectCore o
           (visit(o.set_quantifier) if o.set_quantifier),
           ("#{o.projections.map { |x| visit x }.join ', '}" unless o.projections.empty?),
           ("FROM #{visit(o.source)}" if o.source && !o.source.empty?),
-          ("WHERE #{o.wheres.map { |x| visit x }.join ' AND ' }" unless o.wheres.empty?),
+          ("WHERE #{o.wheres.map { |x| accept x }.join ' AND ' }" unless o.wheres.empty?),
           ("GROUP BY #{o.groups.map { |x| visit x }.join ', ' }" unless o.groups.empty?),
           (visit(o.having) if o.having),
         ].compact.join ' '