Removed trailing spaces (#2038, #2299)

Examples: Setting up style before bindings, so in complex binding (vulkan/dx12) it isn't miles away from the context creation.

Examples: SDL2+Vulkan: Fixed application shutdown which could deadlock on Linux + Xorg. (#2181)

Examples: Misc comments mainly related to GLFW callbacks. (#1759)

Examples: Vulkan: Fixed some minor discrepency in the SDL+Vulkan example to match the Glfw+Vulkan example. (cc #2097)

Examples: Using "dear imgui" terminology in all examples headers/comments + fix minor typo.

Examples: Using fully qualified "Dear ImGui" name in window titles.

Examples: Tweaked the main.cpp example structure for all examples. (There are a few hidden agendas here: 1) I would like to avoid encouraging people from using the implicit "Debug" window, and promote using Begin/End. In spite of my best attempt, there are a few feature of the upcoming docking system that cannot work 100% properly for the implicit Debug window, so future proof let's not put that feature in the spotlight too much for new users. 2) Moved dumb hardcoded positions into a single spot that can be replaced with a viewport relative position and not affect other demo windows. 3) Calling ShowDemoWindow before anything else, also for the benefit of a specific docking demo which will have an ordering constraint which is not really problematic in a real app but shouldn't be put forward in the demo.

Examples: Vulkan: nverted the parameters to ImGui_ImplVulkan_RenderDrawData() to be consistent with other bindings.

Examples: Renamed imgui_impl_sdl2.cpp to imgui_impl_sdl.cpp (#1870) + changelog bits

Examples: Renamed example folders. (#1870)