Fixed project files so it compiles out of the box on both Debug and Release

Full list of changes:

NetYamlNative.vcproj
 - Changed C++ include path to be relative
 - Removed Linker library directory (not needed and an absolute path)
 - Changed so the Release is a .dll (was set to .exe)
 - Added preprocessor directive YAML_DECLARE_STATIC to Release

NetYaml.csproj
 - Changed Release to allow unsafe code