Initial work on marshalling/unmarshalling SOAP types.

So far added:
* fixed.14.4
* char
* date

soap/types.go

@@ -0,0 +1,60 @@
+package soap
+
+import (
+	"errors"
+	"fmt"
+	"strconv"
+	"time"
+	"unicode/utf8"
+)
+
+func MarshalFixed14_4(v float64) (string, error) {
+	if v >= 1e14 || v <= -1e14 {
+		return "", fmt.Errorf("soap fixed14.4: value %v out of bounds", v)
+	}
+	return strconv.FormatFloat(v, 'f', 4, 64), nil
+}
+
+func UnmarshalFixed14_4(s string) (float64, error) {
+	v, err := strconv.ParseFloat(s, 64)
+	if err != nil {
+		return 0, err
+	}
+	if v >= 1e14 || v <= -1e14 {
+		return 0, fmt.Errorf("soap fixed14.4: value %q out of bounds", s)
+	}
+	return v, nil
+}
+
+func MarshalChar(v rune) (string, error) {
+	if v == 0 {
+		return "", errors.New("soap char: rune 0 is not allowed")
+	}
+	return string(v), nil
+}
+
+func UnmarshalChar(s string) (rune, error) {
+	if len(s) == 0 {
+		return 0, errors.New("soap char: got empty string")
+	}
+	r, n := utf8.DecodeRune([]byte(s))
+	if n != len(s) {
+		return 0, fmt.Errorf("soap char: value %q is not a single rune", s)
+	}
+	return r, nil
+}
+
+func MarshalDate(v time.Time) (string, error) {
+	return v.Format("2006-01-02"), nil
+}
+
+var dateFmts = []string{"2006-01-02", "20060102"}
+
+func UnmarshalDate(s string) (time.Time, error) {
+	for _, f := range dateFmts {
+		if t, err := time.Parse(f, s); err == nil {
+			return t, nil
+		}
+	}
+	return time.Time{}, fmt.Errorf("soap date: value %q is not in a recognized date format", s)
+}