fix doxygen warnings
Merge pull request #348 from tjhei/doxygen_fixes

fix doxygen warnings
Fix copyright years in doc/users/doxygen.html

The year 2013 is already included in the range 2012 - 2014.
Add instantations for class RungeKutta.
Merge pull request #352 from Rombur/fix_step_52

Add instantations for class RungeKutta.
Merge pull request #350 from felgru/doxygen

Fix copyright years in doc/users/doxygen.html
Added clear_current_row to TableHandler incase the current time step is rejected.