Residual diagnostics

Moved pull request from GitHub. Creates diagnostics for users to view while inputting residual observations

geomagio/residual/Calculation.py

@@ -151,7 +151,7 @@ def calculate_D_absolute(
         average_mark,
         meridian,
         mark_azimuth,
-        azimuth,
+        (average_mark - meridian),
     )