Tidying up README, moved entries to FAQ, updated screenshots, removed comma in title.

Fix merge issue on master.

Merge branch 'master' into viewport ...

# Conflicts:
#	imgui.cpp

Window, Focus, Popup: Fixed an issue where closing a popup by clicking another window with the _NoMove flag would refocus the parent window of the popup instead of the newly clicked window.

Moved setting up NavHideHighlightOneFrame from lower-level ClosePopupToLevel() to CloseCurrentPopup() with an explanation. (Followup on 68d3e13)

Docs: various updates, rewording, clarifying the purpose of a PR.

Internals: Popups: Renamed CurrentPopupStack to BeginPopupStack which is much less ambiguous.

Internals: Popups: EndMenu() calls ClosePopupToLevel(g.CurrentPopupStack.Size) which is more correct.

Internals: Popup related comments. Renamed the misleading internal ClosePopup() function. Added bool* test to BeginPopupModal in demo.

Viewport, DPI: Now using DpiScale from the ImGuiPlatformMonitor array instead of calling Platform_GetWindowDpiScale() before the platform window creation. Might even tentatively see if things work out without Platform_GetWindowDpiScale. (#1676)

Tests: Changed prototype of ImGuiTestEngineHook_ItemAdd to match functions called in same spot. Made ButtonBehavior submit fallback item info if ItemAdd() was not called (for resize grips, resize borders, scrollbar, columns, etc.)

Merge branch 'master' into viewport ...

# Conflicts:
#	imgui.h

Comments, minor tweaks.

Metrics: Fixed crash when viewports are disabled (g.MouseLastHoveredViewport is never set).

Tabs: Fixed support for drag and drop ImGuiButtonFlags_PressedOnDragDropHold. (#261) incorrectly missing from the merge from Docking branch.

Internals: Windows hidden with HiddenFramesRegular (but NOT HiddenFramesForResize) preserve their SizeContents, so restoring a auto-resize window after it's been hidden by tabs won't reset its size for a frame. Arguable. Let's see how it goes. (Followup to b48e295)

Contents size is preserved while a window collapsed. Fix auto-resizing window losing their size for one frame when uncollapsed.

Demo: Using Tabs in Style Editor and Simple Layout example. + Adding missing early out in About and Documents examples.

BeginTabBar: Fix to push the expected ID into the ID stack (instead of a hash's hash). (#261)

Demo: Fix collateral damage of 54a60aa

Demo: Fix collateral damage of 54a60aa

Merge branch 'master' into viewport ...

# Conflicts:
#	imgui.cpp
#	imgui_internal.h

Added BETA api for Tab Bar/Tabs widgets. (#261, #351) (merged this feature from the from Docking branch so it can be used earlier as as standalone feature) ...

- Added BeginTabBar(), EndTabBar(), BeginTabItem(), EndTabItem(), SetTabItemClosed() API.
- Added ImGuiTabBarFlags flags for BeginTabBar().
- Added ImGuiTabItemFlags flags for BeginTabItem().
- Style: Added ImGuiCol_Tab, ImGuiCol_TabHovered, ImGuiCol_TabActive, ImGuiCol_TabUnfocused, ImGuiCol_TabUnfocusedActive colors.
- Demo: Added Layout->Tabs demo code.
- Demo: Added "Documents" example app showcasing possible use for tabs.

Added ImGuiWindowFlags_UnsavedDocument window flag to append '*' to title without altering the ID, as a convenience to avoid using the ### operator. (merged from Docking branch)

Using named flags instead of 0 + shallow formatting tweaks from other branches.

Merge branch 'master' into viewport ...

# Conflicts:
#	imgui.cpp
#	imgui_demo.cpp

Added io.ConfigWindowsMoveFromTitleBarOnly option. Still is ignored by window with no title bars (often popups). This affects clamping window within the visible area: with this option enabled title bars need to be visible. (#899) ...

Tweaked default value of style.DisplayWindowPadding from (20,20) to (19,19) so the default style as a value which is the same as the title bar height.

Renamed io.ConfigResizeWindowsFromEdges to io.ConfigWindowsResizeFromEdges and removed its [Beta] mark. Resizing windows from edge is now enabled by default (io.ConfigWindowsResizeFromEdges=true). Note that it only works _if_ the back-end sets ImGuiBackendFlags_HasMouseCursors, which the standard back-end do.

Tests: Adding imgui-test engine hooks (experimental) to provide missing widget state to the testing system.

Merge branch 'master' into viewport ...

# Conflicts:
#	imgui.cpp
#	imgui_internal.h