remove win32 configs from all the externals, so it shouldn't happen again by accident.

- all files converted to unix line endings
- files from other subsystems and most of system have been removed
- include/SFML/System.hpp and include/SFML/Network.hpp modified to
  not include removed stuff
- IpAddress.*pp renamed to IPAddress.*pp to workaround git apply bug
  with case-only renames

Place bundled SFML include paths before others

This allows to build with bundled SFML when system SFML (of another
version) is installed

Note warnings may still be generated by code in Externals if it is included into warning-enabled code (this is the case for libusb).
Also, quiet an intellisense warning in wxWidgets caused by using __w64 for an inapplicable type.

* Currently there is no DEBUGFAST configuration. Defining DEBUGFAST as a preprocessor definition in Base.props (or a global header) enables it for now, pending a better method. This was done to make managing the build harder to screw up. However it may not even be an issue anymore with the new .props usage.
* D3DX11SaveTextureToFile usage is dropped and not replaced.
* If you have $(DXSDK_DIR) in your global property sheets (Microsoft.Cpp.$(PlatformName).user), you need to remove it. The build will error out with a message if it's configured incorrectly.
* If you are on Windows 8 or above, you no longer need the June 2010 DirectX SDK installed to build dolphin. If you are in this situation, it is still required if you want your built binaries to be able to use XAudio2 and XInput on previous Windows versions.
* GLew updated to 1.10.0
* compiler switches added: /volatile:iso, /d2Zi+
* LTCG available via msbuild property: DolphinRelease
* SDL updated to 2.0.0
* All Externals (excl. OpenAL and SDL) are built from source.
* Now uses STL version of std::{mutex,condition_variable,thread}
* Now uses Build as root directory for *all* intermediate files
* Binary directory is populated as post-build msbuild action
* .gitignore is simplified
* UnitTests project is no longer compiled