Examples: Visual Studio: Updated default platform toolset+sdk in vcproj files from v100+sdk7 (vs2010) to v110+sdk8 (vs2012). This is mostly so we can remove reliance on DXSDK_DIR for the DX10/DX11 example, which if existing and when switching to recent SDK ends up conflicting and creating warnings.

Examples: VS: Made project paths independant of SolutionDir so they can be built aside from the solution.

example_glfw_vulkan was missing a reference to imgui_widgets.cpp (#2071, #2036)

Examples: Renamed example folders. (#1870)