gitignore

[NPatch]

Opening the solution in VS leaves a ton of working changes that could be mostly avoided. How about we add a gitignore for the unneeded stuff like:

.vs
Debug
imgui.ini
*.vcxproj.user

There's also the main vcxproj which can show up due to toolset changes but nothing we can do about that. Still a big difference to discard one item prior to a pull.