Add BC6 support to nvtt lib and utils.

- Use 3x3 eigensolver for initial fit in ZOH.  Slightly better perf and RMSE than power method.
- Remove use of double precision in ZOH - speeds up by 12%.
- Fixed RGBM encoding that was broken for HDR images.
- Use gamma-2.0 space for RGBM for HDR images (improves precision in darks).
- Use UNORM instead of TYPELESS formats when saving a DX10 .dds file.  The TYPELESS formats break most viewers.
- Cleaned up warnings in ZOH code.
- Command-line utils will warn if you give them an unrecognized parameter.
- Added VS2010 profiling results.

project/vc10/nvcompress/nvcompress.vcxproj

@@ -352,6 +352,9 @@
     </None>
   </ItemGroup>
   <ItemGroup>
+    <ProjectReference Include="..\bc6h\bc6h.vcxproj">
+      <Project>{c33787e3-5564-4834-9fe3-a9020455a669}</Project>
+    </ProjectReference>
     <ProjectReference Include="..\nvcore\nvcore.vcxproj">
       <Project>{f143d180-d4c4-4037-b3de-be89a21c8d1d}</Project>
       <ReferenceOutputAssembly>false</ReferenceOutputAssembly>