pipoint: fix some spelling mistakes.

filter.go

@@ -22,7 +22,7 @@ type Lowpass struct {
 }
 
 // StepEx feeds v into the filter and returns the filtered value.  Tau
-// is the filter coefficent, where 1.0 is no filtering and 0.0 is no
+// is the filter coefficient, where 1.0 is no filtering and 0.0 is no
 // pass through.
 func (l *Lowpass) StepEx(v, tau float64) float64 {
 	l.Acc = tau*v + (1-tau)*l.Acc

latlon.go

@@ -46,7 +46,7 @@ func AsRad(deg float64) float64 {
 	return deg * (math.Pi / 180)
 }
 
-// AsDeg convers radians to degrees.
+// AsDeg converts radians to degrees.
 func AsDeg(rad float64) float64 {
 	return rad * (180 / math.Pi)
 }

param_test.go

@@ -90,6 +90,6 @@ func TestParamNumber(t *testing.T) {
 	p.SetInt(17)
 	assert.Equal(t, p.GetInt(), 17)
 
-	// Setting to a non-number casues an error.
+	// Setting to a non-number causes an error.
 	assert.Error(t, p.Set(&TestParamStructT{}))
 }