Merge pull request #96 from dariomanesku/master

Fixed sin(y) sign in mtxRotateXY().
Added AABB overlap test.
Cleanup.
Moved fpumath to bx.
Updated 07-callback example.
Switched logic to prefer DX11 renderer on Win8.
Added C99 compatible header.
Updated README.
Added interfaces to C99 header.
Cleanup.
Added documentation into C99 header.
Cleanup.
Updated C99 header.
Fixed type.
Added shared library support.
Fixed mip calculation.
Added bgfx platform C99 header.
defining round function isn't required for vs2013 or newer.
Merge pull request #99 from fluffyfreak/nanovg_vs2013_fix

Defining round function isn't required for vs2013 or newer.
Workaround C4127 MSVC level 4 warning.