Examples: SDL: Initial attempt at implementing the viewport/platform api. (WIP/test API) (#1542) ...

ImGui_ImplSDL2_Init() now takes a SDL GL context.

Examples: GLFW + OpenGL3: Initial attempt at implementing the viewport/platform api. (WIP/test API) (#1542)

Examples: DX11 + Win32: Initial attempt at implementing the viewport/platform api. (WIP/test API) (#1542)

Examples: Misc tweaks/fixes.

Merge branch 'master' into examples_refactor ...

# Conflicts:
#	examples/opengl3_example/imgui_impl_glfw_gl3.cpp
#	examples/sdl_opengl3_example/imgui_impl_sdl_gl3.cpp

Examples: Fix d749d49 missing the deletion code. (#1217)

Examples: OpenGL3: Create the VAO in the render function so the setup can more easily be used with multiple shared GL context. (#1217)

Examples: DirectX12: Merged to new example format, imgui_impl_dx12.cpp contains the DX12 stuff, couple with imgui_impl_win32.cpp

Merge branch 'master' into examples_refactor

Examples: DirectX12: Tweaked assertion to more accurately represent what it wants to say. (#301)

Update README.txt

Examples: DirectX12: Fixed shutdown issue. (#301)

Examples: DirectX12: Merge, various styling tweaks, update for 1.60 wip, synchronized Win32 features with other examples. (#301)

Examples: DirectX12: Removed from current solution which is meant to be VS2010 compatible for now (will change soon).

Merge branch 'jdm3_master'

Examples: DirectX10, DirectX11: Simplified main example code.

Simplified .gitignore list

Simplified .gitignore list

Examples: Titles/comments in headers

Merge branch 'master' into examples_refactor

Examples: SDL: Using %SDL2_DIR% in the .vcproj instead of %SDL_DIR%, the earlier is more standard.

Examples: Using SDL2_DIR instead of SDL_DIR (more standard).

Examples: Added SDL+Vulkan example, the abstraction worked here :) (ref #1367)

Examples: Vulkan: Formatting and tweaks (to match SDL's main).

Merge branch 'master' into examples_refactor

Examples: OpenGL: Cast call to glPolygonMode(). (#1628).

Examples: Mouse cursor handling comments/tweaks to homogenize. (#1495)

Examples: GLFW: Added support for mouse cursors (ImGui::GetMouseCursor() value and WM_SETCURSOR message handling). (#1495)

Examples: GLFW*: Renamed GLFW callbacks exposed in .h to not include GL2/GL3/Vulkan in their name.

Examples: DirectX 9,10,11: Inputs: Added support for mouse cursors (ImGui::GetMouseCursor() value and WM_SETCURSOR message handling). (#1495)