0.8.5

AirSensor 0.8.5

• Fixed pat_aggregate() to always return a "regular" time axis with no
  missing timesteps.
• Restored example_sensor dataset.
• Additional unit tests.

AirSensor 0.8.4

• Added another QC function -- PurpleAirQC_hourly_AB_03().
• Modified pat_monitorComparison()
  • simplified function signature by removing unused color and shape parameters
  • added FUN to specify which QC algorithm to apply
  • added distanceCutoff specifying the radius within which to search for a
    nearby monitor.

AirSensor 0.8.3

• Restored unit tests for pat_filterDate().