* Handle duplicate methods and constructors in semantic analysis

* Ordering

	First define methods and operator overloads.

	Do enumerations and constants.

	Process function bodies

	Can a constant_expression invoke overloaded operators?
	Explicit user-defined conversions?

* Visibility

	I am not processing visibility yet.

* Tokenizer

	Propagate file/location to upper layers

* Error handling

	Normalize, and use Tokenizer location 

* Enumerations

	Currently I am not resolving enumerations.

	Either I track them with `RecordEnum' as I do with classes,
	structs and interfaces or I rewrite the code to visit type
	containers and `walk' the enums with this process. 

* Known problems:

  Can not parse try {} catch {}

	Have not figured out why.

  Cast expressions

	They should should use:

		OPEN_PARENS type CLOSE_PARENS

	instead of the current production which is wrong, because it
	only handles a few cases.

	Complex casts like:

		Array r = (string []) object

	Wont be parsed.

  
* Interfaces

	For indexers, the output of ix2.cs is different from our
	compiler and theirs.  They use a DefaultMemberAttribute, which
	I have yet to figure out:

	.class interface private abstract auto ansi INTERFACE
	{
		.custom instance void [mscorlib]System.Reflection.DefaultMemberAttribute::.ctor(string) 
		= ( 01 00 04 49 74 65 6D 00 00 )                      // ...Item..
		...
	}

* Interface indexers

	I have not figured out why the Microsoft version puts an
	`instance' attribute, and I am not generating this `instance' attribute.