Build with errors in Visual Studio 2015 (undefined M_PI)

[mbk74]

Hi guys
Please fix examples/protonect/CMakeLists.txt. In 177 replace with this
ADD_DEFINITIONS(-DRESOURCES_INC -D_USE_MATH_DEFINES)

_USE_MATH_DEFINES - should be defined in project

[xlz]

_USE_MATH_DEFINES was removed in #361 51a569f . @fran6co

[mbk74]

Anyway I couldn't build in Visual Studio 2013/2015 without this definition.