changes by @soeroesg:
- cleaner CMakeLists, not only GCC-specific anymore
- adaptations for Visual Studio
- CMake refactored Examples into own CMakeLists
- CMake refactored Thirdparty dependencies
- CMake target-specific linking libraries
- CMake installable package to be used in other projects
- guarded Unix-only headers
- changed usleep to std::sleep
- changed OpenSSL MD5 to hashlibpp MD5, added hashlibpp library in thirdparty folder
- MapPoint.cpp: changed float Distances[N][N] array to std::vector<std::vector>
- LoopClosing.h: changed bool mnFullBAIdx; to size_t
- added build and run scripts
- PnPsolver.h -- is this needed? seems to be deleted on upstream