* MethodDef.cs: Add named param table and methods to get named param

    * MethodDef.cs: Add named param table and methods to get named param
	positions. Add method to get named local variables slot
	number. Make sure param_lists aren't null when defining them. Add
	specialname and rtspecialname attributes if the method being
	defined is named '.ctor' or '.cctor'. Add new method for creating
	signatures using a list of typerefs.
	* GlobalMethodRef.cs: Use new CreateSignature method that takes an
	array of typerefs.
	* MethodRef.cs: Use new CreateSignature method
	* InstrTable.cs: Use INSTR_LOCAL and INSTR_PARAM tokens for
	instructions that take local and param operands.

svn path=/trunk/mcs/; revision=14503