Readme, comments, dear imgui prefixes

Synced/merged minor cruft from docking branch to minimize drift. AFAIK the only meaningful no-op change is that the call UpdateHoveredWindowAndCaptureFlags() was moved above UpdateMouseMovingNewFrame() to match what docking branch has been doing for a while.

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: Vulkan: Fixed warnings. (#2480)

Vulkan: Fix not incrementing semaphore index. (#2472, #2071)

Vulkan: Bits. Using IM_ALLOC/IM_FREE instead of new[] / delete[].

Vulkan: Removed requirement for user to pass their own render buffer storage to ImGui_ImplVulkan_RenderDrawData(), this is managed internally.

Vulkan: Added ImageCount to InitInfo structure (!= MinImageCount) will be needed for viewports. Renamed FramesQueueSize -> ImageCount. (#2472, #2071)

Vulkan, Viewports: Fix for resizing viewport windows crashing. (#2472)

Vulkan: Renaming demo/helper structures. Tidying up examples main.cpp.

Vulkan: Renaming, we want InitInfo to source MinImageCount which is the "source" value (so viewport creation can use this). Made ImGui_ImplVulkan_DestroyFrameRenderBuffers public. (#2071)

Vulkan: Added extra parameter to ImGui_ImplVulkan_RenderDrawData(). User is in charge of owning/storing 1 ImGui_ImplVulkan_FrameRenderBuffers per in-flight rendering frame. Removed ImGui_ImplVulkan_SetFramesQueueSize. (#2461, #2348, #2378, #2097, #2071, #1677)

Vulkan: More renaming. Comments.

Examples: Vulkan: Merged helpers into ImGui_ImplVulkanH_CreateWindowData. Removed ImGui_ImplVulkan_InvalidateFrameDeviceObjects from API. Comments. (#2071)

Examples: Vulkan: Renamed QueuedFramesCount to FramesQueueSize. Moved Framebuffer, Backbuffer to FrameData structure. (#2071)

Examples: Vulkan: Updated Changelog, removed debug code, tweaked code, made GLFW/SDL match each others. Initialize FrameDataForRender fields. Added Assertion. Clearing fields on DestroyFrameData(). (#2071)

Examples: Vulkan: Fixed tabs->space, removed extraneous braces and empty lines. (#2071)

Examples: Vulkan: Added calls to supports runtime changing back buffer count. (#2071)

Tabs to Spaces, comments.

Examples: Vulkan: Added shader sources/references in the .cpp source.

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

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: GLFW: User previously installed GLFW callbacks are now saved and chain-called by the default callbacks. (#1759)

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

Examples: GLFW: VS2015 project link with legacy_stdio_definitions.lib in order to link with the precompiled VS2010 GLFW3.lib we provide. (#2010, #2043, #2091)

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.

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

Examples: Vulkan: Fixed handling of VkSurfaceCapabilitiesKHR::maxImageCount = 0 case. Tweaked present mode selections.