v2 updated

[@lx]

I have some good news! I have been able to add DirecSound, XAudio2 and
XAPO API as well as some samples for these API.

The current raw coverage of v2 is :
- DXGI
- Direct9 : 1 sample
- Direct11 : 1 sample
- Direct10 : 1 sample
- Direct10.1
- Direct2D : 2 samples
- DirectWrite : 1 sample
- DirectSound : 1 sample
- XAPO
- XAudio2 : 1 sample

I have also added an Error assembly that is optional and loaded at
runtime when there is an exception. This assembly contains all error
messages that are available in DirectX (and in fact, the whole Win32
API). The assembly is not used directly by the SlimDX2 core assembly
but is loaded at runtime.

DirectSound is not complete in terms of extensions, but is working for
basic streaming.

XAudio2 and XAPO are more complete (even with available reverb/fx
effects) but they still need some effort.

By "raw coverage", I mean that 100% of the raw DirectX API is
generated and accessible. For all extensions and correct mapping,
there are still lots of work to do. I'm going to write a more detailed
TODO list for each assembly, but everything seems to work very well so
far! Most of the remaining work is to add mapping to the XIDLToCSharp
and add extension code.

Because I had to handle new parsing cases, the tools have been
improved. XAPO and XAudio2 were fairly easy to add and generate.