Error: assuming signed overflow does not occur when assuming that (X -
c) > X is always false [-Werror=strict-overflow]

Examples: Added OS X example (moved from ios, added support for os x)

Squashed commits:
[34cc3b7] Adds osx example. (+6 squashed commits)
Squashed commits:
[20330f2] Uses glfw by brew install.
[0427861] Renames imguiex folder name to imguiex-ios
[f9e27e5] Renames ios_example to apple_example.
[44f8fe3] Updates the glfw header/library path.
[919f279] Renames target from imguiex to imguiex-ios since there is already a imguiex-osx target now.
[24395f5] Adds osx example.

Style: removed WindowFillAlphaDefault which was confusing and redundant, baked into WindowBg color. Renamed TooltipBg > PopupBG. (#337)

bg_alpha parameter of 5-parameters version of Begin() is an override,
however that function may become obsolete someday.

Fixed InputTextMultiLine(), ListBox(), BeginChildFrame(): outer frame not honoring bordering (following #462)

Added ImGuiWindowFlags_AlwaysUseWindowPadding flag to ensure non-border child window uses window padding (#462)

stb_textedit.h: proposal for upstream PR to allow custom move-left/move-right handlers (following #473)

IO: Added unused MultiSelectUsesSuperKey dummy field to convey semantic for OS X compatible behavior (#473)

InputText/IO: Added WordMovementUsesAltKey , ShortcutsUseSuperKey for OS X Compatible behavior (#473)

IO: Added "Super" keyboard modifiers (corresponding to Cmd on Mac and Windows key in theory although the later is hard to read) (#473)

NB: Value not used.