Refactor

some tasks since we are nearing the first phase
- [x] merge contants_23 and constants_24 into a single class
- [x] have the conversions methods return dataframes where appropriate
- [x] have the calculations class return dataframes where appropriate
- [x] modify plotting linpot functions to support the new .csv file structure
- [x] reduce complexity of the plot wheel load vs time
- [ ] implement switch statement into the visualizer to select the type of plot we want to make, pass this in as arg
- [ ] rename plot to plot_scatter