* introduce offset for faster linearization of non-growing axes
* added traits::is_inclusive and constexpr bool inclusive() methods for builtin axes
* bug fixes for fill method when weight array is used with non-inclusive axis and when growing axes are used
* bug fix of axis::options::test(...)
* coverage tested with gcc-8, updated CONTRIBUTING.md with coverage info
* rename get_size to axes_rank and move axes buffer to axes.hpp
* added fill experiments
* faster and simpler fill_impl
* faster specializations for linearize_value
- Tests and benchmarks now only include the headers they really need.
- Warnings turned off for tests that compile with external boost libs that are not warning free
* fetching google benchmark with cmake
* use new thread-safe accumulator in histogram_parallel_filling
* update boost, root and gsl benchmarks to use google benchmark