Merge branch 'context' ...

# Conflicts:
#	examples/allegro5_example/main.cpp
#	examples/directx10_example/main.cpp
#	examples/directx11_example/main.cpp
#	examples/directx9_example/main.cpp
#	examples/marmalade_example/main.cpp
#	examples/opengl2_example/main.cpp
#	examples/opengl3_example/main.cpp
#	examples/sdl_opengl2_example/main.cpp
#	examples/sdl_opengl3_example/main.cpp
#	examples/vulkan_example/main.cpp

Nav: Toward automatically mapping keyboard input. Renamed ImGuiNavInput_PadXXX to ImGuiNavInput_XXX. Renamed ImGuiNavInput_KeyXXX to ImGuiNavInput_KeyXXX_ (internal). (#787)

Merge branch 'master' into context

Merge branch 'master' into navigation ...

# Conflicts:
#	imgui.cpp
#	imgui_internal.h

Drag and Drop: TreeNode as drop target displays rectangle over full frame. Added optional internal storage for item display rect. Will expose later. (#1597, #143)

Internals: Refactored bool LastItemRectHovered into flags. (#1597)

Nav: Comments, removed extraneous parameter.

Nav: SetItemDefaultFocus() doesn't make the navigation cursorr highlight visible. Renamed NavInitResultExplicit to NavInitRequestFromMove. (#787)

Nav: Maintaining a NavActivatePressedId field that widget can conveniently use along with NavActivateDownId.

Nav: Debugging code. (#787)

Nav: Minor tidying up. (#787)

Internals: ImRect: Added IsInverted() helper.

ImRect: added IsInverted() helper.

Nav: TreeNode: Added ImGuiTreeNodeFlags_NavCloseFromChild flag, allow closing a TreeNode() from any of child. The explicit flag is not great, perhaps allowing some form of inheritance would help. (#787, #1079)

Nav: When focusing a parent window while closing a popup, hide its highlight for one frame to avoid potential double highlight and flicker with the common pattern of menu items leading to the opening other windows. (#787)

Nav: Fixed Selectable/MenuItem Nav Highlight from using rounding when outer highlight stays square. (#787)

Merge branch 'master' into navigation

Internals: Renamed CloseInactivePopups() to a better ClosePopupsOverWindow(). Exposed in imgui_internal.h

Nav: SetFocusID() clears NavInitRequest for consistency (repro would a same frame interaction / race condition). (#787)

Internals: Nav: Extracted code into IsWindowNavFocusable(). (#787)

Nav: Child window is restored on focus when returning to layer 0 or refocusing. This is a little experimental and potentially error-prone right now. (#787, vaguely relate to ~#727) Ideally we should maintain a non-sorted last-focused list that include childs windows.

Merge branch 'master' into context

Nav: Added proper version of ImGuiWindowFlags_NavFlattened that handles scrolling nicely. Marked as private as I'm not happy with the name. (#787)

Nav: Internals: Renamed RootNavWindow to NavRootWindow (#787)

Nav: Refactor NavMoveResult** flags into ImGuiNavMoveResult structure as we are going to want two instances of it. (#787) (+1 squashed commits) ...

+ store window inside result.

Internals: Nav: Renamed ImGuiNavForward enum (#787)

Nav: Comments, added enum to clarify NavForward code. (#787)

Merge branch 'master' into navigation

Nav: Cleaning up + using ImGuiInputSource source enum instead of a silly bool. (#787)

Nav: Keyboard: Added CTRL+TAB (and CTRL+Shift+TAB) style window selection. (#787)