Move to Visual Studio 2015

[shuffle2]

Currently this PR is in tiny commits so they can be looked at easily.
Once reviewed it will be squashed down.

[shuffle2]

blocked on #2218

[waddlesplash]

@shuffle2: FWIW, with latest VS2015, I just merged this into master locally and it built with no additional changes. Maybe the issues are solved?

[waddlesplash]

Other than the volatile problems, LGTM.

[shuffle2]

The commit is ready now, once @Parlane fixes the buildbot this should be merged to keep master building.

[shuffle2]

After reviewing the state of CRT libraries going forward, I decided not to package parts of it with dolphin anymore (the so-called "app-local deployment" method). App-local deployment was originally not going to be supported at all but as of VS2015 RTM, support is maintained.
So while it's technically possible to do, I think it is much better to go with the "proper" method of telling people to run VCRedist (vcredist_x64.exe in our case). We could package this with dolphin, host it somewhere, or just give people instructions. Doing it this way ensures dolphin references the most up-to-date version of the binaries, prevents us from having to ship dozens(!) of DLLs with dolphin, and automatically deploys the correct files for the version of windows they're running on. I also doubt dolphin will be the first app doing this that people will try to execute, so it's likely most people won't even notice.

[MayImilae]

They'll notice. They will SO notice!