Merge branch 'master' into docking ...

# Conflicts:
#	examples/imgui_impl_sdl.cpp
#	imgui.cpp
#	imgui_internal.h

Examples: OpenGL3: Cast compile/link status to GLboolean (#2112, #2125) ...

Some OpenGL loaders/bindings do not allow comparisons between GLints and GLbooleans.

Examples: imgui_imp_opengl3.cpp explicit casting for overly aggressive glbinding compatibility. (#2112) [@hesiod]

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_dx9.cpp
#	examples/imgui_impl_opengl2.cpp
#	examples/imgui_impl_opengl3.cpp
#	examples/imgui_impl_vulkan.cpp

Examples: Using "dear imgui" terminology in all examples headers/comments + fix minor typo.

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/example_glfw_opengl3/main.cpp
#	examples/imgui_impl_opengl3.cpp
#	imgui.cpp
#	imgui_internal.h

Examples: OpenGL: Added support for glew and glad OpenGL loaders out of the box. (#2001, #2002). Changelog, tweaks, applied changes to SDL+OpenGL3 example.

WIP on configurable OpenGL loader. (#2001, #2002)

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_opengl2.cpp
#	examples/imgui_impl_opengl3.cpp
#	imgui.cpp

Examples: Cast to ImTextureID instead of void* when assigning to TexId. Applied to all examples. (#2015)

imgui_impl_opengl3: Advertised as a ES2/ES3 renderer. Defaults to ES3 on Android. Default on "#version 300 es" on ES 3. (#2002, #1873)

imgui_impl_opengl3.cpp Using GLES3 on IOS instead of gl3w. (#2002, #1873) ...

Not modifying the main.cpp yet because we need to test GL ES 3 context creation on iOS (only imgui_impl_opengl3.cpp was tested).

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_opengl3.cpp
#	imgui.cpp

imgui_impl_opengl3: Comments. (#1987)

Examples: imgui_impl_opengl3.cpp Using #ifdef GL_SAMPLER_BINDING instead of if (glBindSampler) (#1985)

Examples: OpenGL3: Tweaks, added changelog. (#1941)

Examples; imgui_impl_opengl3.cpp to work with Emscripten (#1941) ...

* Add some ifdefs to add emscripten specific params and includes

* Update imgui_impl_opengl3.cpp

* Update imgui_impl_opengl3.cpp

* Update imgui_impl_opengl3.cpp

* replace __EMSCRIPTEN_BUILD__ with __EMSCRIPTEN__

* replace GLFW_INCLUDE_ES3 with direct header

* removing useless glfw include

* Making call to glPolygonMode() optional

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_opengl3.cpp
#	imgui.cpp
#	imgui.h
#	imgui_draw.cpp
#	imgui_internal.h

Examples: include for intptr_t on tdm-gcc + mingw32 (#1936) + mouse buttons comments

Examples: OpenGL3: Added shaders more versions of GLSL + made the example app default to GL 3.0 + GLSL 130 (instead of GL 3.2 + GLSL 150) unless on Mac. (#1938, #1900, #1513, #1466, etc.)

OpenGL3: Added error output when shaders fail to compile / link. (#1938)

Merge branch 'master' into viewport ...

# Conflicts:
#	imgui.cpp

Examples: Comments, Demo: Log early out, TODO. (#1553)

Merge branch 'master' into viewport ...

# Conflicts:
#	imgui.cpp

Examples: Comments, bits of documentation

Merge branch 'master' into viewport ...

# Conflicts:
#	imgui.cpp

Examples: OpenGL3: Remove misleading or unnecessary "#version 150" strings.

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_opengl2.cpp
#	examples/imgui_impl_opengl2.h
#	examples/imgui_impl_opengl3.cpp
#	examples/imgui_impl_opengl3.h
#	imgui.cpp
#	imgui.h

Internals: Added GetItemID(), GetFocusID() for consistency. Made GetActiveID() inline. Comments, fixed typos, demo tweaks.

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_dx10.cpp
#	examples/imgui_impl_dx10.h
#	examples/imgui_impl_dx11.cpp
#	examples/imgui_impl_glfw.cpp
#	examples/imgui_impl_glfw.h
#	examples/imgui_impl_opengl2.cpp
#	examples/imgui_impl_opengl2.h
#	examples/imgui_impl_opengl3.cpp
#	examples/imgui_impl_sdl.cpp
#	examples/imgui_impl_sdl.h
#	examples/imgui_impl_vulkan.h
#	examples/imgui_impl_win32.cpp