Fix spelling (#29)

Author: BoRuDar

fieldSetter.go

@@ -87,7 +87,7 @@ func setSlice(t reflect.Type, v reflect.Value, val string) error {
 	)
 
 	if size == 0 {
-		return fmt.Errorf("setSlice: got emtpy slice")
+		return fmt.Errorf("setSlice: got empty slice")
 	}
 
 	switch t.Elem().Kind() {

fieldStetter_test.go

@@ -375,7 +375,7 @@ func TestSetValue_EmptySlice(t *testing.T) {
 	testValue := " "
 
 	err := setValue(fieldType, fieldVal, testValue)
-	assert(t, "setSlice: got emtpy slice", err.Error())
+	assert(t, "setSlice: got empty slice", err.Error())
 }
 
 func TestSetValue_Unsupported(t *testing.T) {

flagProvider.go

@@ -49,7 +49,7 @@ type FlagSet interface {
 }
 
 // WithFlagSet allows the flag.FlagSet to be provided to NewFlagProvider.
-// This allows compatability with other flag parsing utilities.
+// This allows compatibility with other flag parsing utilities.
 func WithFlagSet(s FlagSet) FlagProviderOption {
 	return func(fp *flagProvider) {
 		fp.flagSet = s