Implement iter_plot for iterative plotting

iter_plot can be called on an EasyPlot instance to loop through a series of x, y data sets stored either as 2D Numpy Arrays or Dictionaries.
Plot parameters supplied to iter_plot can either be single valued (same value applied to all plots) or Dictionaries, or 1D Lists/Arrays (separate parameter values applied to each plot)
Bugfixes in iter_plot implementation
Code cleanup
Restructure folder layout and create __init__.py
Setup.py, documentation and project structure