Merge branch 'master' into viewport ...

# Conflicts:
#	imgui.cpp
#	imgui.h

Demo: Added comments / tweaks related to the popups.

Window: Added ImGuiWindowFlags_NoBackground flag for consistency and to ease creating new flag combinations. Added ImGuiWindowFlags_NoDecoration helper flag which is essentially NoTitleBar+NoResize+NoScrollbar+NoCollapse. (#1660)

Demo: Testing return value of BeginTabBar() for consistency.

Merge branch 'master' into viewport ...

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

Merge branch 'master' into docking ...

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

Renamed misc/stl/imgui_stl.h,.cpp to misc/cpp/imgui_stdlib.h in prevision for other files.(#2035, #2096) ...

Added misc/README file.

Viewport: Added ImGuiConfigFlags_ViewportsDecoration to re-enable platform decoration (#1542)

Viewport: Added ImGuiConfigFlags_ViewportsDecoration to re-enable platform decoration (#1542)

Docking: Kept ImGuiDockNodeFlags_PassthruDockspace and removed ImGuiDockNodeFlags_PassthruInEmptyNodes, ImGuiDockNodeFlags_RenderWindowBg. Doesn't include ImGuiDockNodeFlags_NoDockingInCentralNode. (#2109)

Docking: Added ImGuiDockNodeFlags_PassthruDockspace mode (subdivided in three flags: ImGuiDockNodeFlags_NoDockingInCentralNode, ImGuiDockNodeFlags_PassthruInEmptyNodes, ImGuiDockNodeFlags_RenderWindowBg). Added internal facility for register a rectangular hit-test hole in window. Updated DockSpace demo accordingly. (#2109)

Docking: Added ImGuiDockNodeFlags_NoOuterBorder, tweaked DockSpace demo to remove window border. Made docking splitter use the same standard setting as resizing from edges. (#2109)

Docking: Renamed "DocRoot/DocumentRoot" to "CentralNode", more self explanatory. Moved Splitter update higher up in DockNodeUpdate() + minor misc tweak. (#2109)

Docking: Added ImGuiDockNodeFlags_NoDockingInsideDocRootNode flag. Honoring ImGuiDockNodeFlags_NoSplit in child node is already split (so we can use DockBuilder and then lock the layout). Added those options to the demo. (#2109)

Docking: Fixed DockSpace() child window displaying a scrollbar behind the node backgrounds. Rename ImGuiCol_DockingBg to ImGuiCol_DockingEmptyBg. Added ImGuiDockNode::IsLeaftNode(). (#2109)

Docking: Renamed io.ConfigDockingWithKeyMode to io.ConfigDockingWithShift.

Docking: Demo: Displaying a message if master docking flag is disabled. + DockSpace() early out + comments.

Style: Added style.TabRounding setting.

Merge branch 'viewport' into docking

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_win32.cpp
#	examples/imgui_impl_win32.h
#	imgui.cpp

Renamed SetScrollHere() to SetScrollHereY(). Kept redirection function (will obsolete).

Docking: Renamed SetNextWindowDock() to SetNextWindowDockId(). Added GetWindowDockId().

ArrowButton(): Fixed arrow shape being horizontally misaligned by (FramePadding.y-FramePadding.x) if they are different. ...

Demo: Added extra usage of AlignTextToFramePadding() in a more visible section.

Docking: Renamed ImGuiDockSpaceFlags to ImGuiDockNodeFlags. Clarified in comments/demos that DockSpace creates a Node. Renamed IsExplicitRoot to IsDockSpace. Assert against explicitly calling DockSpace twice in a frame.

Docking: work to allow programmatic control of dock nodes, various refactor + assert fix. Probably broke something (but I haven't found what yet!)

Fixed bad merge (a82be53) where we lost the version number in Docking branch + moved Docking related API together for now.

Docking: Changed DockSpace() signature to take an ID, as ID will frequently be used by other API it makes more sense to let the user compute it.

Merge branch 'viewport' into docking ...

# Conflicts:
#	docs/CHANGELOG.txt
#	imgui_demo.cpp
#	imgui_internal.h

Merge branch 'master' into viewport ...

# Conflicts:
#	imgui.cpp
#	imgui_internal.h

DragFloat: Disabled using power curve when one edge is FLT_MAX (broken in 1.61). Disabled setting a default drag speed when one edge is FLT_MAX. (#2024)