Use dispatch_once() to initialize all singleton objects.
Added a default: case in the Mac hosting view to fix a static analyzer warning.
Updated deprecated NSCalendarUnit values to use the new names. Fixed issue #93.
Updated deprecated calendar identifiers with the new preferred values.
Replace deprecated NSDate method with NSDateFormatter.
Replaced a deprecated math constant with the preferred value.
Fixed some deprecated method warnings.
Fixed a memory leak in CPTScatterPlot.