* CairoPlot.py: -Class structure was refactored as it was noted that
                                 the new ScatterPlot was able to render DotLine and 
                                 FunctionPlots;
                                -Following the refactoring, the bounds associated with
                                 a FunctionPlot chart (x_bounds) now define a closed
                                 interval, which means the last value is also taken
                                 taken into account;
                                -Error bars support was added to the ScatterPlot;
                                -All h_* and v_* parameters have been changed to x_*
                                 and y_*.
* tests.py:     -FunctionPlot tests were changed to fit the new bounds;
                                -All tests were changed to reflect the h_* and v_* to 
                                 x_* and y_* parameter change.