WIP Menus: Added example menu, move app examples to a sub-menu (#126) ...

NB: menus do not react on click yet, with popup-style blocking of other
inputs yet

WIP Menus: BeginMenuBar() return false on window without a menu bar (#126)

Renamed ImGuiWindowFlags_Menu to ImGuiWindowFlags_ChildMenu

WIP Menus: fixed case where zero-sized display (e.g. minimised window) clips popups/menus and asserted (#126)

WIP Menus: fixed hovering handling of menus from menu bars (#126)

WIP Menus: menu bars. Still inconsistency with hovering scheme. Will probably follow what Windows does. (#126).

Moved internal window flags to higher bit-count

WIP Menus: further fixes for resizing (#126)

Selectable(): horizontal filling not declared to ItemSize() so Selectable(),SameLine() works and we can best auto-fit the window

Comments

Popups: fix to allow child popups to be opened from a normal window without an intermediate popup window.

Selectable: using window->WindowPadding() to work within non-padded child windows

Window: fixed auto-fit calculation mismatch of whether a scrollbar will be added by maximum height clamping. ...

Also honor NoScrollBar in the case of height clamping, not adding extra
horizontal space.

Style editor: fixed slider for indent spacing.

Window: fixed child window sizing lag + minimum size clamping lag

Popups: child popups (menus) hidden on their first frame the same way as regular popup

Popups: made OpenPopup()/close loops reclaim focus and update popup position. It is generally a mistake but it's now more easy to understand

ImVector: tweak growth strategy

Metrics: do not count free(NULL) calls. Settings: contiguous allocations for ImGuiIniData.

Metrics: metrics window shows popups list

Examples: Console: example uses standard malloc/free, makes more sense as a copy & pastable example

Added IO.MetricsAllocs counter (number of memory allocations

Popups: fixed child windows within popups vs handling of sub menus. Added examples.

Popups: identifying popups by their id to avoid conflict when recycling popup durnig same same (CloseCurrentPopup followed by Open+Begin)

Comments

Added io.MetricsActiveWindows counter (#213)

ImFontAtlas: doesn't clear input data, left to the application. (#224)

ImFontAtlas: Fix toward allowing to add extra font without clearing existing one (need to comment out ClearInputData) (#224)

ImFontAtlas: added ClearFonts(), making the different clear funcs more explicit (#224)

Window title text centering tweaks, RenderTextClipped() now has different args for pos_max and clip_max #222