Release v1.0.2

• Revamped package to move away from object oriented implementation to functional
• Functional implementation now returns a tuple of two lists for x and y values
• Split adaptive Runge-Kutta implementation from conventional Runge-Kutta with adaptive_gerk()
• Removed all methods to get approximations, errors and make plots
• Reduced the number of condition boolean parameters to just one parameter to cover all conditions
• Replaced all Exception classes with just one Exception class GerkError
• Renamed some parameters