Update README.md

README update, updated binaries, sponsors

Examples: Vulkan: Fix (something changed in GLFW not including vulkan.h, was unwillingly relying on that)

Warning fix. (#1565)

Updated version to 1.60 WIP to emphasis on the addition of required calls CreateContext/DestroyContext + merged the massive Navigation branch (#1565, #787)

Merge branch 'context' ...

# Conflicts:
#	examples/allegro5_example/main.cpp
#	examples/directx10_example/main.cpp
#	examples/directx11_example/main.cpp
#	examples/directx9_example/main.cpp
#	examples/marmalade_example/main.cpp
#	examples/opengl2_example/main.cpp
#	examples/opengl3_example/main.cpp
#	examples/sdl_opengl2_example/main.cpp
#	examples/sdl_opengl3_example/main.cpp
#	examples/vulkan_example/main.cpp

Merge branch 'navigation'

Nav: Documentation tweaks. (#787)

Nav: Examples: Added commented out io.NavFlags |= ImGuiNavFlags_EnableKeyboard to all examples. (#787)

Nav: Keyboard is now automatically mapped based on io.KeyDown[]. (#787)

Removed comments

Added ImGuiKey_Space, mapped in every examples. Will be required for navigation. (#787)

Nav: Toward automatically mapping keyboard input. Renamed ImGuiNavInput_PadXXX to ImGuiNavInput_XXX. Renamed ImGuiNavInput_KeyXXX to ImGuiNavInput_KeyXXX_ (internal). (#787)

Nav: Comments, guides.

Merge branch 'master' into context

ImVec2: added [] operator. This is becoming desirable for some types of code, better added sooner than later.

ImVec2: added [] operator. This is becoming desirable for some types of code, better added sooner than later.

Merge branch 'master' into navigation ...

# Conflicts:
#	imgui.cpp
#	imgui_internal.h

Drag and Drop: TreeNode as drop target displays rectangle over full frame. Added optional internal storage for item display rect. Will expose later. (#1597, #143)

Internals: TreeNode: Renaming local to be more consistent with other widgets.

Internals: Refactored bool LastItemRectHovered into flags. (#1597)

Nav: Comments, removed extraneous parameter.

Nav: SetItemDefaultFocus() doesn't make the navigation cursorr highlight visible. Renamed NavInitResultExplicit to NavInitRequestFromMove. (#787)

Examples: SDL+GL3: Added Navigation keyboard mapping. (#787)

Merge branch 'master' into navigation

Examples: SDL: Using SDL_GetPerformanceCounter() / SDL_GetPerformanceFrequency() to handle framerate over 1000 fps properly. Noticed bad inputs artefacts in Nav branch at 2000 fps without this. (#996)

Examples: SDL2: Enabling vsync. Using scancode consistently, fixed keyboard weirdness.

Examples: Organized header files to make available features more visible.

Nav: Sliders and Drags are toggle activated instead of requiring user to cross Cross/Space. (#787)

Nav: DragBehavior: Tweaks (to take the noise out of the next commit).