Examples: SDL: Fix for Emscripten/Android/iOS on Docking branch.

Merge branch 'master' into docking ...

# Conflicts:
#	imgui_internal.h
#	imgui_widgets.cpp

Tabs: Moved Tab List Popup to left-side to match docking button. Highlight selected tab. (#261, #351)

Tabs: Non-docking tab bars are storing names to allow tab list button + whole style scaling. Added ImGuiTabBarFlags_TabListPopupButton flag to show a popup button on manual tab bars. Locking FramePadding for the scope of a tab-bar to avoid sheering/clipping of tab item. Made scaling of tab ellipsis less awkward. (#261, #351)

ImGuiTextBuffer: Fix size() to allow using ImGuiTextBuffer with resize(0) patterns.

RadioButton: Fixed label horizontal alignment to precisely match Checkbox(). + Internals: Checkbox, RadioButton: Single call to ItemSize() for flow layout purpose.

Internals: DragScalar, SliderScalar: Calling ItemSize before ItemAdd as with every other widgets so we can more easily rearrange the signature of ItemXXX functions (toward allowing non-rounded sizes for scaling and flow layout).

Fonts: Fixed crash if FontGlobalScale is zero. Correctly debug naming default font if not 13 px. Demo: Moved PopupRounding along with other rounding values. Metrics: Displaying indexes with idx to be correct / less misleading.

Docking: Fixed less of node size/pos caused by 1f2bdd37 (#2109)

Docking: Fixed dragging docked window with _NoMove flag (#2325)

Merge branch 'master' into docking ...

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

Internals: Exposed internal SetWindowPos to imgui_internal.h (for imgui-test)

Revert part of change from 5536eded. Fixed drag and drop in docking branch. (#2331, reopening #2325)

Removed io.DisplayVisibleMin/DisplayVisibleMax (which were marked obsolete and removed from viewport/docking branch already).

Removed io.DisplayVisibleMin/DisplayVisibleMax (which were marked obsolete and removed from viewport/docking branch already).

Examples: Made imgui_impl_win32 drag gdi32.lib for GetDeviceCaps(). (#2327)

Examples: OpenGL3: Using GLSL 4.10 shaders for any GLSL version over 410 (e.g. 430, 450). (#2329) [@BrutPitt]

Merge branch 'master' into docking (enable range_select merge) ...

# Conflicts:
#	imgui.cpp
#	imgui_internal.h

Internals: Tracking dummy select scope id (currently always zero) to facilitate merging of the range_select branch. (#1861)

Internals: Minor changes to TreeNodeBehavior() and Selectable() for the benefit of fhe range_select branch. (#1861)

Internals: Track ActiveIdHasBeenPressed (similar to ActiveIdHasBeenEdited). This is currently mostly for the benefit of the range_select branch. (#1861)

Fixed Clang/Win32 warning.

Merge branch 'master' into docking ...

# Conflicts:
#	imgui.cpp
#	imgui.h
#	imgui_internal.h

Docking: Extracted code into a DocknodeUpdateTabListMenu() functions + minor other changes.

Comments. Fix duplicate entries in About box. Synchronize a few small changes from Master branch.

Merged from Docking branch: Various small changes, comments, typos fixes, moved blocks. To reduce overall drift. Should be no-op.

Merged from Docking branch: non-const ImVec2[] operator.

Merge branch 'master' into docking ...

# Conflicts:
#	imgui.cpp

Docking: Builder: Added DockBuilderSetNodePos, DockBuilderSetNodeSize, allow DockBuilderAddNode creating floating node (dockspace requires ImGuiDockNodeFlags_Dockspace) (#2109)

Docking: VisibleWindow of a node spread its _NoMove attribute to the node (fixed dragging or undocking of dock node host from collapse button). (#2325, #2109)