Support generic local functions

[siegfriedpammer]

The support for local functions implemented in #1586 does not cover generic local functions.

A first batch of test cases:

class Program<CT>
{
	public static void Main(string[] args)
	{
		A(args);

		int A<T>(T a)
		{
			return 1;
		}
	}

	public static MT Get<MT>(string key, MT defaultValue)
	{
		return Do();

		MT Do()
		{
			Console.WriteLine(key);
			return defaultValue;
		}
	}

	public static CT TypeParameter()
	{
		return A();

		CT A()
		{
			return default(CT);
		}
	}
}