Examples: Fixed warnings for Clang

Examples: Added STB_IMAGE_STATIC in examples to avoid conflicting implementation. Relate to #109

OpenGL3 example: fix growing of VBO

New and better Set[Next]Window(Pos|Size|Collapsed) API. ...

Removed rarely useful SetNewWindowDefaultPos() in favor of new API.

OpenGL example: allow resizing window.

OpenGL3 example: fixed mouse handling.

Fix Clang warning with offsetof() macro? Added -Wall in OpenGL 3 example.

Setup Travis CI integration with Clang + -Wall in Makefiles

OpenGL3 example: unregistered mouse callback for mouse click-release faster than frame interval.

Examples: DirectX11: moved shader to be close to its usage location,

Examples: OpenGL3: cleaned up to match features of OpenGL2 example

Examples: adding title to the top of each examples. Cleaning up file headers.

Examples: removed LICENSE file from MSVC project.

fixed indentation mix, removed some unused code, updated different callback using the example_opengl code.

added opengl3 sample, mix from @ocornut and @thelinked

Examples: OpenGL: fix accessing libraries via ProjectDir instead of SolutionDir

DirectX11 example: fixed projection matrix offset.

DirectX9/DirectX11 example: fixed window initially showing an hourglass cursor.

Example apps: accumulate mouse wheel to accodomate for slow framerate.

DirectX11 example: further tweaks/massaging (-15 lines). Syncing example.

Tab->Spaces :( visual studio can't even be trusted for that, oh thanks.

DirectX11 example: closing all handler/resources in Cleanup.

Removed Microsoft IME handler in examples, too confusing. Moved to imgui.cpp instruction block.

Tab->Spaces :(

Fixed DirectX11 example Release build include

Fixed DirectX11 example to compile with whatever Visual Studio version user has

Added DirectX11 example application (code is too long!)

Examples: created single .sln solution for all example projects.

Example code: warning fix + comments.

Updated example code.