Remove 5 unused `Bit` methods and reduce visibility of 2

src/BizHawk.Common/Bit.cs

@@ -18,43 +18,16 @@ namespace BizHawk.Common
 			return new Bit((uint)rhs);
 		}
 
-		public static implicit operator Bit(uint rhs)
-		{
-			Debug.Assert((rhs & ~1) is 0, "higher bits can't be used");
-			return new Bit(rhs);
-		}
-
-		public static implicit operator Bit(byte rhs)
-		{
-			Debug.Assert((rhs & ~1) is 0, "higher bits can't be used");
-			return new Bit(rhs);
-		}
-
 		public static implicit operator Bit(bool rhs)
 		{
 			return new Bit(rhs ? (byte)1 : (byte)0);
 		}
 
-		public static implicit operator long(Bit rhs)
-		{
-			return rhs._val;
-		}
-
 		public static implicit operator int(Bit rhs)
 		{
 			return (int)rhs._val;
 		}
 
-		public static implicit operator uint(Bit rhs)
-		{
-			return rhs._val;
-		}
-
-		public static implicit operator byte(Bit rhs)
-		{
-			return (byte)rhs._val;
-		}
-
 		public static implicit operator bool(Bit rhs)
 		{
 			return rhs._val != 0;

src/BizHawk.Common/Extensions/IOExtensions.cs

@@ -99,12 +99,12 @@ namespace BizHawk.Common.IOExtensions
 			}
 		}
 
-		public static void WriteBit(this BinaryWriter bw, Bit bit)
+		internal static void WriteBit(this BinaryWriter bw, Bit bit)
 		{
 			bw.Write((bool)bit);
 		}
 
-		public static Bit ReadBit(this BinaryReader br)
+		internal static Bit ReadBit(this BinaryReader br)
 		{
 			return br.ReadBoolean();
 		}