Grand test fixup (#138)

* start fixing up tests

* fix up tests + automate with drone

* fiddle with linting

* messing about with drone.yml

* some more fiddling

* hmmm

* add cache

* add vendor directory

* verbose

* ci updates

* update some little things

* update sig

vendor/github.com/dsoprea/go-exif/gps.go

@@ -0,0 +1,56 @@
+package exif
+
+import (
+	"errors"
+	"fmt"
+	"time"
+
+	"github.com/golang/geo/s2"
+)
+
+var (
+	ErrGpsCoordinatesNotValid = errors.New("GPS coordinates not valid")
+)
+
+type GpsDegrees struct {
+	Orientation               byte
+	Degrees, Minutes, Seconds float64
+}
+
+func (d GpsDegrees) String() string {
+	return fmt.Sprintf("Degrees<O=[%s] D=(%g) M=(%g) S=(%g)>", string([]byte{d.Orientation}), d.Degrees, d.Minutes, d.Seconds)
+}
+
+func (d GpsDegrees) Decimal() float64 {
+	decimal := float64(d.Degrees) + float64(d.Minutes)/60.0 + float64(d.Seconds)/3600.0
+
+	if d.Orientation == 'S' || d.Orientation == 'W' {
+		return -decimal
+	} else {
+		return decimal
+	}
+}
+
+type GpsInfo struct {
+	Latitude, Longitude GpsDegrees
+	Altitude            int
+	Timestamp           time.Time
+}
+
+func (gi *GpsInfo) String() string {
+	return fmt.Sprintf("GpsInfo<LAT=(%.05f) LON=(%.05f) ALT=(%d) TIME=[%s]>", gi.Latitude.Decimal(), gi.Longitude.Decimal(), gi.Altitude, gi.Timestamp)
+}
+
+func (gi *GpsInfo) S2CellId() s2.CellID {
+	latitude := gi.Latitude.Decimal()
+	longitude := gi.Longitude.Decimal()
+
+	ll := s2.LatLngFromDegrees(latitude, longitude)
+	cellId := s2.CellIDFromLatLng(ll)
+
+	if cellId.IsValid() == false {
+		panic(ErrGpsCoordinatesNotValid)
+	}
+
+	return cellId
+}