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

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

Examples: Allegro, Apple, DirectX9/10/11, Glfw+Vulkan :Added support for horizontal mouse wheel. (#1463)

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

Examples: Using IM_OFFSETOF macro. + Comments

Examples: Added a bunch of comments/referencs related to io.WantCaptureMouse, io.WantCaptureKeyboard (#1262, #1237, #1219, #635, #1058, #1051, #912, #533, #703, #446, #459, #364, #213, #52, and more)

IO: io.MousePos needs to be set to ImVec2(-FLT_MAX,-FLT_MAX) when mouse is unavailable/missing. Previously ImVec2(-1,-1) was enough but we'll now accept negative mouse coordinates.

Added a void* user_data parameter to Clipboard function handlers. (#875)

Examples: Accessing ImVector fields directly, feel less stl-ey and fix renderer side assert when render list only contains a callback (#810)

IO: Added "Super" keyboard modifiers (corresponding to Cmd on Mac and Windows key in theory although the later is hard to read) (#473) ...

NB: Value not used.

Trim trailing spaces

FAQ and comments about the use of ImTextureID (#562, #561, #521, #510, #497, #475 ...)

Examples: Not clearing input data/tex data in atlas (will be required for dynamic atlas anyway). Effectively fix resizing in DX examples. ...

+ Standardized comments.

Examples: Header comments.

Examples: Most examples apps detect if ImDrawIdx was changed to 32-bits instead of 16

Examples: Possibly clarified the intent of imgui_impl_* files.

Examples: comment on setting the RenderDrawListsFn function.

Merge remote-tracking branch 'origin' into 2015-03-antialiased-primitives ...

Conflicts:
	imgui.cpp

Allegro 5 example: removed public domain mark, MIT as the rest, with @bggd approval

Allegro 5 example: converted for indexed rendering.

Allegro 5 example: fixed uv coordinate of non-default texture.

Allegro 5 example: handling of hardware and software mouse cursor rendering.

Allegro 5 example: fixed key modifiers, keyboard input, clipping, added pagedown/pageup.

Allegro 5 example: formatting, match other example structure, fixed mouse buttons.

Allegro 5 example: main.cpp matches other examples. added window title.

Allegro5 example: added example from https://github.com/bggd/a5imgui_example