Merge branch 'master' into docking ...

# Conflicts:
#	docs/CHANGELOG.txt
#	examples/imgui_impl_opengl3.cpp
#	imgui.cpp
#	imgui_internal.h

Comments, todo list, remove trailing spaces.

Examples: OpenGL: Added a dummy GL call + comments in ImGui_ImplOpenGL3_Init() to detect uninitialized GL function loaders early, and help users understand what they are missing. (#2421)

Version 1.70 WIP

Merge branch 'master' into docking ...

# Conflicts:
#	docs/CHANGELOG.txt
#	examples/example_win32_directx10/main.cpp
#	examples/example_win32_directx11/main.cpp
#	examples/example_win32_directx12/main.cpp
#	examples/example_win32_directx9/main.cpp

Version 1.69, comments, typos

Internals: Fixed Navigation from reaching ImGuiItemFlags_Disabled items (#211) + Examples comments

Merge branch 'master' into docking ...

# Conflicts:
#	examples/imgui_impl_glfw.cpp
#	examples/imgui_impl_sdl.cpp

Examples: GLFW, SDL: Preserve DisplayFramebufferScale when main viewport is minimized. (This is particularly useful for the viewport branch because we are not supporting per-viewport frame-buffer scale. It fixes windows not refreshing when main viewport is minimized.) (#2416)

Merge branch 'master' into docking ...

# Conflicts:
#	examples/example_win32_directx11/main.cpp
#	examples/example_win32_directx12/main.cpp
#	examples/example_win32_directx9/main.cpp
#	imgui.cpp

Examples: Win32+DirectX: moved helper functions below main.

Viewports: Renamed ConfigViewportsNoParent to ConfigViewportsNoDefaultParent. Fix outdated comments in examples.

Fix typos. (#2413)

Examples: DirectX9: Added support for multi-viewport (#2394)

Merge branch 'master' into docking ...

# Conflicts:
#	imgui_demo.cpp

Examples: DirectX9: Minor changes to match the other DirectX examples more closely. (#2394)

Merge branch 'master' into docking ...

# Conflicts:
#	examples/imgui_impl_opengl3.cpp

Examples: OpenGL: Fix to be able to run on ES 2.0 / WebGL 1.0. [@rmitton, @gabrielcuvillier]

Examples: OpenGL: Comments about versions and loaders. (#2393, #2351)

Examples + Viewport: GLFW: context wasn't set when using multiple windows. (#2392)

Merge branch 'master' into docking ...

# Conflicts:
#	imgui.cpp
#	imgui.h

Merge branch 'allegro-touch' of https://github.com/dos1/imgui into dos1-allegro-touch ...

# Conflicts:
#	examples/imgui_impl_allegro5.cpp

Merge branch 'master' into docking ...

# Conflicts:
#	docs/CHANGELOG.txt
#	examples/imgui_impl_opengl3.cpp
#	imgui_widgets.cpp

Examples: OpenGL: Fix for OSX not supporting OpenGL 4.5, we don't try to read GL_CLIP_ORIGIN even if the OpenGL headers/loader happens to define the value. (#2366, #2186)

Examples: VS: Made project paths independant of SolutionDir so they can be built aside from the solution.

Comments for Linux/Mac (#2117)

Merge branch 'master' into docking

Examples: Vulkan: Rewrote scissor processing to match other examples more closely. Removed extraneous +1 of scissor extent height.

Examples: Vulkan: Support draw_data->FramebufferScale correctly matching a79785c for on Metal/GL2/GL3. (#2306, #1676)

ImFont: Minor adjustment to the structure. ...

Examples: Removed unused variable.