Code cleanup and refactoring to lower CCN.
Fix the bug with sampling log-normal distribution.

Boost introduced a different log-normal distribution sampling function
in boost::random namespace that works as expected. The previous
implementation was using backwards compatible log-normal distribution
with different behaviour.
Uncertainty analysis statistics and reporting.
Add benchmark small tree test for uncertainty analysis and update
documentation.
closes #6
Merge branch 'develop' into coverity-scan

Conflicts:
	doc/monte_carlo_simulations.rst
	doc/todo.rst