Alpha 6: Fixes for installer and DLL woes

For alpha 6, the installer was updated once again in order to more reliably handle different combinations of operating system and Office version.

With alpha 5, I had programmed the installer to determine if the .NET 4.0 runtime files needed to be downloaded and installed. Unfortunately, just after uploading the release, I realized that the installer did a bad job in determining whether the Visual Studio Tools for Office runtime needed to be installed, too.

Alpha 6 now attempts to finally fix it, although I am not 100 % sure yet because things are so complicated when it comes to .NET, VSTO and 32/64 bitness.

In addition, I found out that the 64-bit version of the FreeImage DLL had an external depencency on vcomp120.dll, which is not necessarily present on all computers. I have now re-compiled the DLL without this dependency. For technical details, see this blog post.