(Breaking) Default ImTextureID to use a Im64 instead of void* (#1641)

backends/imgui_impl_dx12.cpp

backends/imgui_impl_dx12.h

backends/imgui_impl_vulkan.cpp

backends/imgui_impl_vulkan.h

docs/CHANGELOG.txt

docs/FAQ.md

examples/example_glfw_vulkan/CMakeLists.txt

examples/example_glfw_vulkan/build_win32.bat

examples/example_glfw_vulkan/build_win64.bat

examples/example_glfw_vulkan/example_glfw_vulkan.vcxproj

examples/example_sdl2_vulkan/build_win32.bat

examples/example_sdl2_vulkan/example_sdl2_vulkan.vcxproj

examples/example_win32_directx12/build_win32.bat

...s/example_win32_directx12/example_win32_directx12.vcxproj

examples/example_win32_directx12/main.cpp

imgui.cpp

imgui.h

imgui_draw.cpp

imgui_widgets.cpp