Viewports, DPI: Renamed config flags. (#1542)

Viewport: Popups, Tooltips can individually request no task bar icons to the platform layer. (#1542)

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_dx10.cpp
#	examples/opengl2_example/imgui_impl_glfw_gl2.cpp
#	examples/opengl3_example/imgui_impl_glfw_gl3.cpp
#	examples/vulkan_example/main.cpp
#	imgui.h

Examples: Added missing calls for ::DestroyWindow, glfwDestroyWindow() + fix old comments.

Viewport: Renamed RenderPlatformWindows() to RenderPlatformWindowsDefault(), tweaked examples and emphasis optional Viewport code path. (#1542)

Examples: OpenGL2: Added multi-viewport support in the OpenGL2 back-end. (#1542) + Metrics: Fix undisplayed flag.

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/sdl_opengl2_example/main.cpp
#	examples/sdl_opengl3_example/main.cpp
#	examples/vulkan_example/main.cpp

Examples: Renamed applications to emphasis on use of GLFW as a platform framework + minor local tweaks

Viewport, Platform: Refactored platform interface. Removed need to use imgui_internal.h in backends. Split viewport into public facing ImGuiViewport and internal structure. Exposing enough data to provide custom tweaked renderers. Renamed handlers, fixed lots of inconsistencies. (#1542, #1042)

Examples Refactor: GLFW: Explicit functions to init GLFW with OpenGL or Vulkan since we cannot read the api hints from glfw.

Examples: Renamed glfw error callback for clarity.

Examples: Renamed glfw error callback so it's more clear what it is.

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

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

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

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.

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)

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

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

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).

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

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)

Examples: Comments to guide people unfamiliar with the librairies used.

Examples: Added more comments near the fonts loading section, to catch common questions and errors (e.g. #1397, #1366, #1341, #1222, #1193, #1115, #951, etc.)