Added FisheryLib.Collections.FishTable and Mono.Cecil extension methods

A bit of refactoring has been done too

Source/FisheryLib/Collections/NibbleArray.cs

@@ -0,0 +1,62 @@
+// Copyright (c) 2023 bradson
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+using System.Runtime.CompilerServices;
+using JetBrains.Annotations;
+
+namespace FisheryLib.Collections;
+
+[PublicAPI]
+public struct NibbleArray
+{
+	private uint _length;
+	private byte[] _data;
+
+	public uint this[uint index]
+	{
+		[MethodImpl(MethodImplOptions.AggressiveInlining)]
+		get
+		{
+			Guard.IsLessThan(index, _length);
+			
+			return (index & 1u) == 0u ? _data[index >> 1] & 0b0000_1111u : (uint)_data[index >> 1] >> 4;
+		}
+		set
+		{
+			Guard.IsLessThan(value, 16u);
+			Guard.IsLessThan(index, _length);
+			
+			_data[index >> 1] = (byte)((index & 1u) == 0u
+				? (_data[index >> 1] & 0b1111_0000u) | value
+				: (_data[index >> 1] & 0b0000_1111u) | (value << 4));
+		}
+	}
+
+	public uint Length
+	{
+		[MethodImpl(MethodImplOptions.AggressiveInlining)]
+		get => _length;
+	}
+
+	public NibbleArray(uint length)
+	{
+		_length = length;
+		_data = new byte[(length + 1u) >> 1];
+	}
+
+	public void Resize(uint newSize)
+	{
+		_length = newSize;
+		Array.Resize(ref _data, (int)(newSize + 1u) >> 1);
+	}
+
+	public void Clear() => _data.Clear();
+	
+	public void Initialize(uint value)
+	{
+		Guard.IsLessThan(value, 16u);
+		Unsafe.InitBlockUnaligned(ref _data[0u], (byte)(value | (value << 4)), (uint)_data.Length);
+	}
+}