Nav: Fixed ButtonBehavior mistakenly setting active id when the Activate button is held and we have a new NavId, which affected browsing some popups (#787)

Merge branch 'master' into navigation ...

# Conflicts:
#	imgui.cpp
#	imgui_internal.h

Begin: Shallow tweak to minimize diff with nav branch

Merged from Navigation branch: ImGuiItemFlags_SelectableDontClosePopup flag

Added VerticalSeparator() entry point in imgui_internal. Seperator() in an horizontal layout context still does that.

Separator(): Tweak Logging so that the separator text is aligned according to tree padding.

Merge branch 'master' into navigation ...

# Conflicts:
#	imgui.cpp
#	imgui_internal.h

Fixed IsItemHovered() - part of the processing has to be done in ItemAdd() because the widget may alter clipping rectangle temporarily.

Nav: Fixed NavDown to open menu from a menu bar (#787)

Merge branch 'master' into navigation

Refactor to move the responsability of SetHovered() to ItemHoverable() - previously IsHovered(). Simpler and the parallel to ItemAdd is clearer with the new name.

Removed another msileading difference between the hovered functions (IsWindowContentHoverable() uses the root window already). Sorry for the commit spam! (making small commit to easily be able to Bisect those in case I make a mistake)

IsItemHovered(), IsHovered(): Shallow tweaks, eventually removed all the braces.

Internals: Moved IsWindowContentHoverable() in the file

IsItemHovered(), IsHovered(): Shallow tweaks to make them more symetrical. Removed one set of braces.

Internals: ButtonBehavior(), IsHovered() moved the responsability of flatten_child higher level to ButtonBehavior() - not super sure about the elegance of this

Nav: Fixed merge cc26db8

Merge branch 'master' into navigation

IsItemHovered(), ItemAdd(): finishing cleaning up, moved the code to IsItemHovered() so ItemAdd() is more lightweight and the two IsXXXHovered functions are now very similar, making their differences less confusing.

ItemAdd(): more re-ordering of tests to match IsHovered() + comments

IsItemHovered(), ItemAdd(): Fixed seemingly unnecessary comparaison of root windows, makes IsItemHovered() more consistent with internal IsHovered(). ...

Original test was added in 6e99688 should not have been using RootWindow in the first place.
The difference between public-facing and internal versions would only be noticeable with overlapped child windows, which doesn't really happen anyway

ItemAdd(): re-ordering the tests, submission should now be faster.

ItemAdd(), not performing computation for IsItemRectHovered() which does them itself, allowing us in the next commit to optimize ItemAdd() and make its logic more consistent with IsHovered().

Moved implementation of Hovered-related functions next to each others + comments, before I attempt to work on them. No functional change here.

Nav: Removed unnecessary combo code (that kept the combo arrow highlighted after reverting to mouse controls). (#787)

Merge branch 'master' into navigation

Fixed not being able to move a window by clicking on one of its child window (#1337, #635), broken by https://github.com/ocornut/imgui/commit/313d388bba42e0634a02b976dcdbae238d25eddc

Removed extraneous ImGui:: prefixes. Declared ColorEditOptionsPopup in imgui_internals.h. Tweaked internal signatures.

Combo: Cleaned up, removed unnecessary code (looks like this part went untouched for a long time!).

Merge branch 'master' into navigation