Support TryWith expressions

[GoogleCodeExporter]

For example,

source <@ try (null:string).Length with | e -> -1 @>

produces

TryWith (PropertyGet (Some (Value (<null>)), Int32 Length, []), e, Value (1), e,
         Value (-1))

Original issue reported on code.google.com by stephen....@gmail.com on 15 Feb 2011 at 1:34