accept 0x(0X) start in 'hexadecimal' tag (#620)

* accept hexadecimal which starts with 0x(0X) optionally

regexes.go

@@ -9,7 +9,7 @@ const (
 	alphaUnicodeNumericRegexString   = "^[\\p{L}\\p{N}]+$"
 	numericRegexString               = "^[-+]?[0-9]+(?:\\.[0-9]+)?$"
 	numberRegexString                = "^[0-9]+$"
-	hexadecimalRegexString           = "^[0-9a-fA-F]+$"
+	hexadecimalRegexString           = "^(0[xX])?[0-9a-fA-F]+$"
 	hexcolorRegexString              = "^#(?:[0-9a-fA-F]{3}|[0-9a-fA-F]{6})$"
 	rgbRegexString                   = "^rgb\\(\\s*(?:(?:0|[1-9]\\d?|1\\d\\d?|2[0-4]\\d|25[0-5])\\s*,\\s*(?:0|[1-9]\\d?|1\\d\\d?|2[0-4]\\d|25[0-5])\\s*,\\s*(?:0|[1-9]\\d?|1\\d\\d?|2[0-4]\\d|25[0-5])|(?:0|[1-9]\\d?|1\\d\\d?|2[0-4]\\d|25[0-5])%\\s*,\\s*(?:0|[1-9]\\d?|1\\d\\d?|2[0-4]\\d|25[0-5])%\\s*,\\s*(?:0|[1-9]\\d?|1\\d\\d?|2[0-4]\\d|25[0-5])%)\\s*\\)$"
 	rgbaRegexString                  = "^rgba\\(\\s*(?:(?:0|[1-9]\\d?|1\\d\\d?|2[0-4]\\d|25[0-5])\\s*,\\s*(?:0|[1-9]\\d?|1\\d\\d?|2[0-4]\\d|25[0-5])\\s*,\\s*(?:0|[1-9]\\d?|1\\d\\d?|2[0-4]\\d|25[0-5])|(?:0|[1-9]\\d?|1\\d\\d?|2[0-4]\\d|25[0-5])%\\s*,\\s*(?:0|[1-9]\\d?|1\\d\\d?|2[0-4]\\d|25[0-5])%\\s*,\\s*(?:0|[1-9]\\d?|1\\d\\d?|2[0-4]\\d|25[0-5])%)\\s*,\\s*(?:(?:0.[1-9]*)|[01])\\s*\\)$"

validator_test.go

@@ -7765,6 +7765,14 @@ func TestHexadecimal(t *testing.T) {
 	errs := validate.Var(s, "hexadecimal")
 	Equal(t, errs, nil)
 
+	s = "0xff0044"
+	errs = validate.Var(s, "hexadecimal")
+	Equal(t, errs, nil)
+
+	s = "0Xff0044"
+	errs = validate.Var(s, "hexadecimal")
+	Equal(t, errs, nil)
+
 	s = "abcdefg"
 	errs = validate.Var(s, "hexadecimal")
 	NotEqual(t, errs, nil)