Add SpreadsheetAbsoluteFactory to read residual spreadsheet format

Pipfile.lock

@@ -934,4 +934,5 @@
             "version": "==3.1.0"
         }
     }
+  }
 }

geomagio/residual/measurement.py

+from typing import Optional
+
+from obspy.core import UTCDateTime
+from pydantic import BaseModel
+
+from .. import pydantic_utcdatetime
+from .MeasurementType import MeasurementType
+
+
+class Measurement(BaseModel):
+    """One angle and time measurement with optional residual.
+
+    Attributes
+    ----------
+    measurement_type: type of measurement.
+    angle: measured angle, decimal degrees.
+    residual: residual at time of measurement.
+    time: when measurement was taken.
+    """
+
+    measurement_type: MeasurementType
+    angle: float = 0
+    residual: float = 0
+    time: Optional[UTCDateTime] = None