Version 0.0.07:
    - add doxygen documentation

Version 0.0.06:
    - fix adjoint problem solver

Version 0.0.05:
    - add interface to choose different stop criteria (by max_iter and functional)
    - add callback interface to use in problems to print number iteration, value
      functional, time of calculation operator

Version 0.0.04
    - fix bug with incorrect calculation in calc_L1 fast
    - stop kriteria by functional in inverse problem added

Version 0.0.03
    - add class SourceFunction with support of fix time SourceFunction

Version 0.0.02
    - rewrite SmoluchowskiSolver class, add SmoluchowskiOperator,
      now cross.cpp use array of index not list
