Added public method to zoom graph to a given midpoint in the graph. Removed private instance variables for originX and originY, replaced with midpoints. Rotating device now zooms to midpoint rather than origin.
Added method to ElevationDataSource to calculate index of trail point nearest a given Lat/Long. This will be used later to find a user's location nearest the trail.
Split some methods into other classes and added a data source protocol in order to make subclassing easier.
Started to add support for switching between Imperial and Metric measurements.
Moved the file path for CSV file into the fetchElevationPoints method for non-static files.