We use negative numbers for the compiler, and leave the possitive
numbers to match the Microsoft numbers:

-1	An Primary Expression was parsed, when a Type was expected.
	This happens because my parser knowledge is limited, and I
	am not good at writing grammars.  It is still an error,
	but if I were smarter, I would have found a Bison/Yacc way
	of handling it.

-2	Internal error, an interface is being defined inside an
	interface (This should never happen).

-3      Constant type is not one of sbyte, byte, short, ushort, int,
	uint, long, ulong, char, float, double, decimal, bool, string, enum
	or null type. 

-5      A search for a name on a Type returned matches that contain
	methods and non-methods.  They have the same name, and I do
	not know how this is possible to begin with.

-6      Generic internal compiler error.

-7      Internal compiler error/library error: no default constructor
	for a built-in type.  Ie, decimal (int 32)

-8	User-defined conversion cannot convert from or to object type.

-9	User-defined conversion cannot convert from or to an interface type.

-10	User-defined conversion cannot convert between types that derive 
	from each other.

-11	Delegate creation expression takes only one argument

-12     More than one integral conversion exists for the type on a
	switch statement.

-13	No return with a value found.  Warning, since we currently
	do not perform flow analysis, and can not tell whether a
	ret is required or not.

-14     Invalid number passed to probe

-15	Can not locate default assembly path

-16	Can not use System.Enum.ToObject (type, ConstantValue) with
	user defined types.

-17     A type has already been defined (try --nostdlib)

-18	Do not know how to generate debugging information for this platform.