Made function for the reading of data from file.
Modified to work with read_file function.
Now including source code and header for read_file function.
Started making the planetary system class, with constructor and time-evolution method.
Made madifications.
Added header-file for RungeKutta4 function.
Made header file and some modifications to the source file.
Uses to test work in progress.
Made modifications.
Python-script for plotting results from output text file.
Made interface with keyword argument to give end time and time step.
Completed time evolution method, with output to text file. Not tested.