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.

Viewport: Reorganized viewport enable flags. Both user + platform + renderer need to enable a flag. (#1542)

Examples: SDL: Fix for pre 2.0.4.

Examples: Updated Makefile and batch files to work with new examples. Using lowercase "gl.h" as it seems this is what Linux wants.

Examples: Added Makefile for SDL+OpenGL2 example. (#1668)

Examples: Added Makefile for SDL+OpenGL2 example. (#1668)

Viewport: Modal display their darkneing/whitening layer over all viewports. (#1542)

Viewport: Various sanity fixes. Popup always inherit viewport from their parent for now. (#1542)

Update README.md

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_glfw.h
#	examples/opengl3_example/imgui_impl_glfw_gl3.cpp
#	examples/sdl_opengl3_example/imgui_impl_sdl_gl3.cpp
#	examples/sdl_opengl3_example/imgui_impl_sdl_gl3.h
#	imgui.cpp

Examples: OpenGL3: Added a way to override the glsl version number through the Init call. (#1667, #1466)

Render: Removed the code that disable render if style.Alpha is 0.0f, it is both incorrect (as style Alpha can be modified mid-frame), not really necessary (just tested that full Alpha = 0 will lead to empty draw lists!) and misleading (bulk of the work was already done).

Viewport: Tracking current viewport we are appending to + added callback in PlatformInterface for DPI purpose (WIP). (#1542)

Removed redundant semi colons. (#1653)

Fixed type cast warning.

Comments, FAQ update.