Update README.markdown

Configure GNU compilers for c++11. (KjellKod#257)

 CMake: CMAKE_INSTALL_PREFIX for Linux (KjellKod#243)

* CMake: CMAKE_INSTALL_PREFIX for Linux

If on Linux system CMAKE_INSTALL_PREFIX is set it overrides
CPACK_PACKAGING_INSTALL_PREFIX key.

* Readme: readme for MinGW building and installation

* Update README.markdown

Git release versioning (KjellKod#163)

* corrected versions to fit release versioning

* fixed comments

Merge pull request KjellKod#83 from KjellKod/duedal-install-target

Duedal install target

Crash Handling:Clang + g3sink support

Merged in changes from development repository.

* threadsafe use of localtime
* changing/retrieving log filename at runtime (using futures)