Slider code syntax tweaks

Fixed parsing of decimal precision back from format string when using %%

SliderFloat() fast-path when power=1.0f (no powf() calls) also makes code easier to read

Refactor SliderFloat() internals into a helper SliderFloatAsInputText() + some comments

Comments and reduced ImGuiTextEditState.InitialText[] to 3 KB (assuming average use case of UTF-8 uses 3 bytes charracters)

Comments

Separator() logs itself as text

Example console keeps focus on input box at all times

Added IsRootWindowFocused(), IsRootWindowOrAnyChildFocused(). Renamed GetWindowIsFocused() to IsWindowFocused()

Child window don't take focus when they first appear (focus left to parent)

Added io.KeyAlt + support in examples apps ...

Currently unused but supported by sample so that more people will have
it set up when menus needs them

WIP marker in uppercase.. (#127)

Update version number, added IMGUI_VERSION, ImGui::GetVersion() (#127)

Fixed more warnings from @bkaradzic

Fixed warnings

Version number

Examples: reference implementations honors drawlist user callbacks.

Examples: README direct the user to the opengl_example

Examples: OpenGL 2/3 examples cleanup to match DirectX9/11 structure.

Examples: DirectX9 example cleanup to match DirectX11 structure.

Examples: DirectX11 example application handles window resizing.

Examples: DirectX9 example application handle window resizing.

Examples: Fixed readme file.

Examples: Refactored directx11_example to be easier to copy & paste into user application.

Examples: Clang warning fix.

Examples: Makefile fixes.

Examples: Clang/Linux warning fixes.

Examples: Tweaks.

Examples: Refactored directx9_example to be eaasier to copy & paste into user application.

Examples: shallow tweaks to match upcoming other examples.