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

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)

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

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

Merge branch 'master' into context

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

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

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/

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)

Examples: Simplified mouse wheel handling. (#1463)

Horizontal mouse wheel: renamed io.MouseHorizWheel to io.MouseWheelH. Reorganized the code in NewFrame(). Examples: Updated GLFW+GL and SDL+GL accordingly. (#1463)

Merge branch 'tseeker/20171127-feature-horiz-wheel' of https://github.com/tseeker/imgui into tseeker-tseeker/20171127-feature-horiz-wheel ...

# Conflicts:
#	examples/sdl_opengl2_example/imgui_impl_sdl_gl2.cpp
#	examples/sdl_opengl3_example/imgui_impl_sdl_gl3.cpp

Examples: GLFW+GL2: Renamed imgui_impl_glfw.* to imgui_impl_glfw_gl2.* for consistency and to emphasis on GL2-ness.

Added ImGuiKey_Insert for future use. Setup in all example bindings. (#1541)

Examples: Using IM_OFFSETOF macro. + Comments

Examples: Visual Studio projects: Disabled extraneous function-level check in Release build.

Examples: Comments about invalid mouse pos.

Examples: Comments, synched some minor drift between examples + stronger suggestion to use StyleColorsDark().

Renamed the emblematic ShowTestWindow() function to ShowDemoWindow(). Kept redirection function (will obsolete).

Horizontal mouse wheel support ...

This patch adds support for the horizontal mouse wheel in ImGui. It
affects windows that can be scrolled, as long as the Ctrl key is not
being pressed.

The scrolling speed has been set empirically so that it matches the
scrolling speed on the Firefox browser when the horizontal wheel is
used.

Internally, it adds a MouseHorizWheel to ImGuiIO, which is then used in
NewFrame to scroll the current window.

The SDL/GL2, SDL/GL3, GLFW/GL2 and GLFW/GL3 examples has been modified
to use it.

Sisyphus says: tweaked comments about not using old-style OpenGL examples (#1459, #1394 etc.)