Merge branch 'master' into viewport (inc Vulkan resize fix merge #1042)

Examples: Vulkan: Passing Queue, QueueFamily to binding. Fixed scissor (fixed in master). ImGui_ImplVulkanH_DestroyWindowData() waits for device to be idle. (#1042)

Misc comments, todos + reintroduced removed ImGuiCol defines under !IMGUI_DISABLE_OBSOLETE_FUNCTIONS wrap.

Examples: DPI: Minor warning fix. (#1676)

Examples: Vulkan: Only resize swap chain and framebuffer once. (#1042)

Examples: Renamed glfw error callback for clarity.

Fixed resize window validation errors with removing frame prerender once and present last but one frame functionality. Frame rate is still similar.

Updated templates, added pull request template.

Style: CloseButton() now display a proper cross. Using Button colors for background. Removed ImGuiCol_CloseButton, ImGuiCol_CloseButtonActive, ImGuiCol_CloseButtonHovered as the closing cross uses regular button colors now. (#707)

Internals: Columns renaming fields

Viewport, DPI: Some early work on per-viewport DPI support. At the moment the easiest way is to replace fonts during the ChangedViewport callback, but down the line we should aim at handling some of it at ImFont level. (#1542, #1676)

Examples: DPI: Portable DPI related helpers in the _Win32 examples. Using one in examples's main.cpp, the GetDpiScale functions are not wired anywhere for now. (#1542, #1676)

Viewport: Fix dropping back viewport not being moved to the front of the window list. (Now that viewport are more tighly coupled to a single root window) (#1542)

Viewport, DPI: Don't activate current window until a viewport has been selected. At this point we'll have the proper size/scale for the current DPI + fix viewport callback when appending to an existing window more than once a frame. (#1542, #1676)

Viewport, DPI: Select viewport before locking style sizes and before handling double-click-on-title-bar to collapse. (#1542, #1676)

ImFont: Added FindGlyphNoFallback. Fixed MergeMode broken by 1ef1acb

Merge branch 'master' into viewport

Viewport,Platform: Added GetWindowDpiScale() platform interface, changes of scale are reflected by positioning and resizing windows in their given viewport. (#1542)

Updated Changelog following merge of #1619 + fixed entry added to wrong version Changelog in 1ef1acb

Merge branch '2018-03-font_offset' into master2

Viewport: Changed signature of ResizeViewport to be consistent with other similar functions.

Viewport: Coupling non-main viewport to one window. Viewport name derived from the window. Added ImGuiConfigFlags_PlatformNoTaskBar, off by default (aka re-established task-bars by default for now). (#1542)

Examples: DPI: Hacked in a quick compile-and-run-everywhere call to SetProcessDpiAwareness(), will need to revisit.

Merge branch 'master' into font_offset

Font: Fixed MergeMode adding duplicate glyphs data instead of reusing existing (broken by 072d6d8)

Fonts: Fixed debug name not being zero-terminated if longer than storage buffer + made buffer slightly longer as well.

Comments, Changelog

Drag and Drop: Increased payload data type to 32 characters. (#143)

Viewport: Disable extra viewports from hosting other windows. (#1542)

Fixed warnings.