Nav: Moving code next to its peers

Nav: Moving the big chunk of code from ItemAdd() to NavProcessItem()

Added ActivateItem(), GetItemID() functions.

Nav: Tidying up activation mechanism so that setting NavActivateId can trigger buttons.

Merge branch 'master' into navigation

Nav: Menus and popups now have move request wrap around vertically (using the move request forward thing added recently). (#787)

SetKeyboardFocusHere() added assert to prevent passing values smaller than -1 as we may have to outlaw them (I think nobody was using that)

Removed obsolete comment.

Merge branch 'master' into navigation

Styles: Added ImGuiStyle::ScaleAllSizes(float) helper to make it easier to have application transition to e.g. High DPI with a matching style.

Nav: Added code to render thin highlight type. (#787)

typo

Nav: Highlight clipped within host window then extruded out. (#787)

Nav: Selectable(): activating selectable also sets NavId + removed the MouseDelta test (added in 43ee5d7, #323) as I don't think it is needed. (#787)

Nav: Added NavMoveResultParentId internal info to record when the parent/context of a given NavId. Useful for various algorithms (currently looking at range selection stuff) (#787)

Nav: Added NavJustNavigatedId internal info to record when we land on a given item after a navigation request, useful for various algorithms (currently looking at range selection stuff) (#787)

Changed the internal name formatting of child windows to use slashes as separator, more readable.

Metrics: Draw window bounding boxes when hovering Pos/Size. List all draw layers, trimming empty commands like Render() does.

Nav: Fixed a crash introduced yesterday.

Nav: Allow to collapse tree nodes with NavLeft and open them with NavRight (#787, #1079)

Nav: Disabled the final axial check when considering candidates in most situations except menubars. ...

It's definitively undesirable inside Menu as we want to catch nav request failures reliably.
I think it may be considered as an option if we find this desirable i some circumstances. Right now ideally I'd remove it totally but with current scoring setup, without it we can't easily reach the Window Close button. (#787)

Nav: It's now possible to navigate sibling of a menu-bar while navigating inside one of their child. If a Left<>Right navigation request fails to find a match we forward the request to the root menu. (#787, #126) ...

Currently the sibling menu is isn't automatically opened, that's still left to it (and even that can be anoying in Windows when the first menu-item is a child menu)

BeginMenu(): fixed logic to distinguish vertical menu from one layed out in a menu bar. Makes MenuItem() in a regular window behave more consistently, and this will be also needed by upcoming menu-navigation changes in the nav branch. (#126, #787)

BeginMenu(): fixed logic to distinguish vertical menu from one layed out in a menu bar. Makes MenuItem() in a regular window behave more consistently, and this will be also needed by upcoming menu-navigation changes in the nav branch. (#126, #787)

Nav: Comments

Nav: Fix typo from 9712a81

Nav: Minor tidying up (adding local variables to be a little more sane).

Nav: Renamed internal field.

Nav: Rectangle rectangle stored per window and per layer as well. Makes things simpler, allows enable us to visualize more data.

Nav: Marked misleading/broken code that will never execute.