Fix some spellings.

OpenRA.Game/FileFormats/Blast.cs

@@ -65,7 +65,7 @@ namespace OpenRA.FileFormats
 			var coded = br.ReadBits(8);
 
 			if (coded < 0 || coded > 1)
-				throw new NotImplementedException("Invalid datastream");
+				throw new NotImplementedException("Invalid data stream");
 			var encodedLiterals = coded == 1;
 
 			// log2(dictionary size) - 6
@@ -160,7 +160,7 @@ namespace OpenRA.FileFormats
 			return ms.ToArray();
 		}
 
-		// Decode a code using huffman table h.
+		// Decode a code using Huffman table h.
 		static int Decode(Huffman h, BitReader br)
 		{
 			var code = 0; // len bits being decoded

OpenRA.Game/FileFormats/CRC32.cs

@@ -111,11 +111,11 @@ namespace OpenRA.FileFormats
 
 		/// <summary>
 		/// A fast (native) CRC32 implementation that can be used on a pinned byte array using
-		/// default polynomal.
+		/// default polynomial.
 		/// </summary>
 		/// <param name="data">		[in,out] If non-null, the.</param>
-		/// <param name="len">		The length of the data data.</param>
-		/// <param name="polynomial">The polynomal to xor with.</param>
+		/// <param name="len">		The length of the data.</param>
+		/// <param name="polynomial">The polynomial to XOR with.</param>
 		/// <returns>The calculated checksum.</returns>
 		public static unsafe uint Calculate(byte* data, uint len, uint polynomial)
 		{

OpenRA.Game/FileFormats/PngLoader.cs

@@ -187,7 +187,7 @@ namespace OpenRA.FileFormats
 			if (bitDepth == 8 && colorType == (PngColorType.Indexed | PngColorType.Color))
 				return PixelFormat.Format8bppIndexed;
 
-			throw new InvalidDataException("Unknown pixelformat");
+			throw new InvalidDataException("Unknown pixel format");
 		}
 	}
 }