qmake QtMosquitto.pro
make

cd build
cmake -D CMAKE_BUILD_TYPE=Debug ../source
make
demo/qtmosquitto-demo

cd build
cmake -D CMAKE_BUILD_TYPE=Debug -D QTDIR=/your_home/Qt/5.x/gcc_64/lib/cmake ../source
make
demo/qtmosquitto-demo

cp build/lib/libqtmosquitto.so* /usr/lib/
cp source/qtmosquitto.hpp /usr/include/

Include the header file:
    #include "qtmosquitto.hpp"

Add the library to your .pro file:
    LIBS += -lqtmosquitto

"C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\vcvarsall.bat"
set PATH=C:\Qt\5.4\msvc2013\bin;%PATH%
cd build
cmake -G "NMake Makefiles" -D CMAKE_BUILD_TYPE=Debug ..\source
nmake
demo\qtmosquitto-demo.exe