* Switched to [`pybind11`](https://github.com/pybind/pybind11) for Python
bindings (thanks to Chris Granade for suggesting this great library),
dropping the dependency on Boost.Python.
* Python package available with `pip`. Added module `tomographer.include` as
well as member `tomographer.version.compile_info` for packaging.
* Any custom figure of merit can be specified as a user-defined function to
the `tomographer.tomorun.tomorun()` in the Python interface
* OpenMP is no longer required neither for `tomorun` nor for the Python
interface. This allows to compile with Apple's default clang compiler on
Mac OS X. (OpenMP can still be used instead of C++11 threads, if
preferred.)