Implemented some clipboard features for WPF and modified C++ project to allow targeting different PlatformToolsets

Some clipboard related features were implemented for WPF and a modification was made to support targeting a different PlatformToolset, e.g. target VS2010 even when building from VS2013.

If you have VS2010, VS2012 and VS2013 you can select the target platform toolset with a drop-down on the project file:

![](http://i.stack.imgur.com/tKMwH.png)

The client computers that will be using CefSharp only has VS2010 runtime installed and it isn't possible at this time to upgrade to a newer version because it would require changes to 10k machines.

For this to work correctly I had to make a custom version of the cef.sdk NuGet package, I had to rename all the folders like this:

CEF\x64\Debug\VS2010

To:

CEF\x64\Debug\v100

Along with this change the other half is changing the project file to use "$(PlatformToolset)" instead of "$(VisualStudioProductVersion)", since the latter is the version of Visual Studio but from VS2013 you can target the VS2010 runtime.