Merge branch 'examples_refactor' into viewport ...

# Conflicts:
#	examples/directx10_example/main.cpp
#	examples/directx11_example/main.cpp
#	examples/directx12_example/main.cpp
#	examples/opengl3_example/main.cpp
#	examples/sdl_opengl2_example/main.cpp
#	examples/sdl_opengl3_example/main.cpp
#	examples/sdl_vulkan_example/main.cpp
#	examples/vulkan_example/main.cpp
#	imgui.h

Renamed ImGuiNavFlags io.NavFlags to ImGuiConfigFlags io.ConfigFlags. (#787)

Renamed ImGuiNavFlags io.NavFlags to ImGuiConfigFlags io.ConfigFlags. (#787)

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

Examples: GLFW+GL2: Moved glfw, gl2 files to root folder, split imgui_impl_glfw_gl2 into _opengl2 and reused imgui_impl_glfw

Examples: GLFW+GL3: Split imgui_impl_glfw_gl3 into imgui_impl_glfw and imgui_impl_gl3 (wip)

Examples: GLFW+GL2/GL3: Added glPixelStorei() calls borrowed from SDL examples.

Obsoleted the io.RenderDrawListsFn callback, you can call your graphics engine render function after ImGui::Render(). Use ImGui::GetDrawData() to retrieve the ImDrawData* to display..(#1599) ...

Examples: Updated examples.

Examples: Added Changelog to make updates easier.

Merge branch 'context' ...

# Conflicts:
#	examples/allegro5_example/main.cpp
#	examples/directx10_example/main.cpp
#	examples/directx11_example/main.cpp
#	examples/directx9_example/main.cpp
#	examples/marmalade_example/main.cpp
#	examples/opengl2_example/main.cpp
#	examples/opengl3_example/main.cpp
#	examples/sdl_opengl2_example/main.cpp
#	examples/sdl_opengl3_example/main.cpp
#	examples/vulkan_example/main.cpp

Nav: Examples: Added commented out io.NavFlags |= ImGuiNavFlags_EnableKeyboard to all examples. (#787)

Nav: Keyboard is now automatically mapped based on io.KeyDown[]. (#787)

Added ImGuiKey_Space, mapped in every examples. Will be required for navigation. (#787)

Nav: Toward automatically mapping keyboard input. Renamed ImGuiNavInput_PadXXX to ImGuiNavInput_XXX. Renamed ImGuiNavInput_KeyXXX to ImGuiNavInput_KeyXXX_ (internal). (#787)

Examples: Organized header files to make available features more visible.

Merge branch 'master' into context

Merge branch 'master' into navigation

Moved extra_fonts/ to misc/fonts/. Moved .natvis file to misc/natvis/ (#1569)

Merge branch 'master' into navigation ...

# Conflicts:
#	imgui.cpp

Examples: Using Dark theme by default. (#707). Tweaked demo code.

Merge branch 'master' into navigation

Examples: Using #include "imgui.h" instead of <imgui.h> appear correct-er as per standard? xcode+clang are very nitpicky there.

Examples: Makefile leave CXX alone, instead leave commented out options. (nb: codeship doesn't seem have clang++)

Examples: Use Clang in old Makefile.

Examples: Synced Makefile comments. Added build/ folder into git ignore list/

Nav: Examples: Glfw+GL3: Added basic gamepad mapping code when io.NavFlags & ImGuiNavFlags_EnableGamepad is set. (will iterate/tweak before spreading to other examples). (#787)

Nav: Examples: DirectX11, Glfw+GL3: Basic code to map keyboard inputs when io.NavFlags & ImGuiNavFlags_EnableKeyboard is set. (will iterate/tweak before spreading to other examples). (#787)

Merge branch 'master' into context

Added imgui.natvis helper for visual studio users. Added to examples projects.

Examples: Updated for reorganized context functions. Calling CreateContext(), DestroyContext() in example code. Removed Shutdown() from binding code. (#1565, #586, #992, #1007, #1558)