Fixed issue with Angular Units (#33)

* Fixed issue with Angular Units

* Removed extra asserts

osr.go

@@ -289,7 +289,6 @@ func (sr SpatialReference) SetAngularUnits(units string, radians float64) error
 func (sr SpatialReference) AngularUnits() (string, float64) {
 	var x *C.char
 	factor := C.OSRGetAngularUnits(sr.cval, &x)
-	defer C.free(unsafe.Pointer(x))
 	return C.GoString(x), float64(factor)
 }
 

osr_test.go

@@ -2,6 +2,7 @@ package gdal_test
 
 import (
 	"fmt"
+	"math"
 	"testing"
 
 	gdal "github.com/seerai/godal"
@@ -24,13 +25,22 @@ func TestLinearUnits(t *testing.T) {
 	assert.NoError(t, err)
 
 	units, value := sr.LinearUnits()
-	assert.NoError(t, err)
 	assert.Equal(t, "metre", units)
 	assert.Equal(t, 1.0, value)
 
 	units, value = sr.TargetLinearUnits("PROJCS")
-	assert.NoError(t, err)
 	assert.Equal(t, "metre", units)
 	assert.Equal(t, 1.0, value)
+	sr.Destroy()
+}
+
+func TestAngularUnits(t *testing.T) {
+	sr := gdal.CreateSpatialReference(nil)
+	err := sr.FromURN("urn:ogc:def:crs:EPSG::4326")
+	assert.NoError(t, err)
 
+	units, value := sr.AngularUnits()
+	assert.Equal(t, "degree", units)
+	assert.Equal(t, math.Pi/180, value)
+	sr.Destroy()
 }